Browsing by Subject "Screening"
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- ItemOpen AccessCulture-confirmed childhood tuberculosis in Cape Town, South Africa: a review of 596 cases(Biomed Central Ltd, 2007) Schaaf, H Simon; Marais, Ben; Whitelaw, Andrew; Hesseling, Anneke; Eley, Brian; Hussey, Gregory; Donald, PeterBACKGROUND:The clinical, radiological and microbiological features of culture-confirmed childhood tuberculosis diagnosed at two referral hospitals are described. METHODS: Cultures of Mycobacterium tuberculosis from children less than 13 years of age at Tygerberg and Red Cross Children's Hospitals, Cape Town, South Africa, were collected from March 2003 through February 2005. Folder review and chest radiography were performed and drug susceptibility tests done. RESULTS: Of 596 children (median age 31 months), 330 (55.4%) were males. Of all children, 281 (47.1%) were HIV-uninfected, 133 (22.3%) HIV-infected and 182 (30.5%) not tested. Contact with infectious tuberculosis adults was recorded in 295 (49.5%) children. Missed opportunities for chemoprophylaxis were present in 117/182 (64.3%) children less than 5 years of age.Extrathoracic TB was less common in HIV-infected than in HIV-uninfected children (49/133 vs. 156/281; odds ratio 0.50, 95% confidence interval 0.32-0.78). Alveolar opacification (84/126 vs. 128/274; OR 1.85, 95%CI 1.08-3.19) and cavitation (33/126 vs. 44/274; OR 2.28, 95%CI 1.44-3.63) were more common in HIV-infected than in HIV-uninfected children. Microscopy for acid-fast bacilli on gastric aspirates and sputum was positive in 29/142 (20.4%) and 40/125 (32.0%) children, respectively. Sixty-seven of 592 (11.3%) children's isolates showed resistance to isoniazid and/or rifampicin; 43 (7.3%) were isoniazid-monoresistant, 2 (0.3%) rifampicin-monoresistant and 22 (3.7%) multidrug-resistant. Death in 41 children (6.9%) was more common in HIV-infected children and very young infants. CONCLUSION: HIV infection and missed opportunities for chemoprophylaxis were common in children with culture-confirmed TB. With cavitating disease and sputum or gastric aspirates positive for acid-fast bacilli, children may be infectious. Transmission of drug-resistant TB is high in this setting.
- ItemOpen AccessDelivery of health care for cardiovascular and metabolic diseases among people living with HIV/AIDS in African countries: a systematic review protocol(BioMed Central, 2016) Watkins, David A; Tulloch, Nathaniel L; Anderson, Molly E; Barnhart, Scott; Steyn, Krisela; Levitt, Naomi SBackground: People living with HIV (PLHIV) in African countries are living longer due to the rollout of antiretroviral drug therapy programs, but they are at increasing risk of non-communicable diseases (NCDs). However, there remain many gaps in detecting and treating NCDs in African health systems, and little is known about how NCDs are being managed among PLHIV. Developing integrated chronic care models that effectively prevent and treat NCDs among PLHIV requires an understanding of the current patterns of care delivery and the major barriers and facilitators to health care. We present a systematic review protocol to synthesize studies of healthcare delivery for an important subset of NCDs, cardiovascular and metabolic diseases (CMDs), among African PLHIV. Methods/design: We plan to search electronic databases and reference lists of relevant studies published in African settings from January 2003 to the present. Studies will be considered if they address one or both of our major objectives and focus on health care for one or more of six interrelated CMDs (ischemic heart disease, stroke, heart failure, hypertension, diabetes, and hyperlipidemia) in PLHIV. Our first objective will be to estimate proportions of CMD patients along the “cascade of care”—i.e., screened, diagnosed, aware of the diagnosis, initiated on treatment, adherent to treatment, and with controlled disease. Our second objective will be to identify unique barriers and facilitators to health care faced by PLHIV in African countries. For studies deemed eligible for inclusion, we will assess study quality and risk of bias using previously published criteria. We will extract study data using standardized instruments. We will meta-analyze quantitative data at each level of the cascade of care for each CMD (first objective). We will use meta-synthesis techniques to understand and integrate qualitative data on health-related behaviors (second objective). Discussion: CMDs and other NCDs are becoming major health concerns for African PLHIV. The results of our review will inform the development of research into chronic care models that integrate care for HIV/AIDS and CMDs among PLHIV. Our findings will be highly relevant to health policymakers, administrators, and practitioners in African settings.
- ItemOpen AccessDiagnostic accuracy, incremental yield and prognostic value of Determine TB-LAM for routine diagnostic testing for tuberculosis in HIV-infected patients requiring acute hospital admission in South Africa: a prospective cohort(2017) Lawn, Stephen D; Kerkhoff, Andrew D; Burton, Rosie; Schutz, Charlotte; Boulle, Andrew; Vogt, Monica; Gupta-Wright, Ankur; Nicol, Mark P; Meintjes, GraemeAbstract Background We previously reported that one-third of HIV-positive adults requiring medical admission to a South African district hospital had laboratory-confirmed tuberculosis (TB) and that almost two-thirds of cases could be rapidly diagnosed using Xpert MTB/RIF-testing of concentrated urine samples obtained on the first day of admission. Implementation of urine-based, routine, point-of-care TB screening is an attractive intervention that might be facilitated by use of a simple, low-cost diagnostic tool, such as the Determine TB-LAM lateral-flow rapid test for HIV-associated TB. Methods Sputum, urine and blood samples were systematically obtained from unselected HIV-positive adults within 24 hours of admission to a South African township hospital. Additional clinical samples were obtained during hospitalization as clinically indicated. TB was defined by the detection of Mycobacterium tuberculosis in any sample using Xpert MTB/RIF or liquid culture. The diagnostic yield, accuracy and prognostic value of urine-lipoarabinomannan (LAM) testing were determined, but urine-LAM results did not inform treatment decisions. Results Consecutive HIV-positive adult acute medical admissions not already receiving TB treatment (n = 427) were enrolled regardless of clinical presentation or symptoms. TB was diagnosed in 139 patients (TB prevalence 32.6%; median CD4 count 80 cells/μL). In the first 24 hours of admission, sputum (spot and/or induced) samples were obtained from 37.0% of patients and urine samples from 99.5% of patients (P < 0.001). The diagnostic yields from these specimens were 19.4% (n = 27/139) for sputum-microscopy, 26.6% (n = 37/139) for sputum-Xpert, 38.1% (n = 53/139) for urine-LAM and 52.5% (n = 73/139) for sputum-Xpert/urine-LAM combined (P < 0.01). Corresponding yields among patients with CD4 counts <100 cells/μL were 18.9%, 24.3%, 55.4% and 63.5%, respectively (P < 0.01). The diagnostic yield of urine-LAM was unrelated to respiratory symptoms, and LAM assay specificity (using a grade-2 cut-off) was 98.9% (274/277; 95% confidence interval [CI] 96.9–99.8). Among TB cases, positive urine-LAM status was strongly associated with mortality at 90 days (adjusted hazard ratio 4.20; 95% CI 1.50–11.75). Conclusions Routine testing for TB in newly admitted HIV-positive adults using Determine TB-LAM to test urine provides major incremental diagnostic yield with very high specificity when used in combination with sputum testing and has important utility among those without respiratory TB symptoms and/or unable to produce sputum. The assay also rapidly identifies individuals with a poor prognosis.
- ItemOpen AccessDiagnostic Utility of New SCAT5 Neurological Screen Sub-tests(2021-02-15) Fuller, Gordon W; Miles, John; Tucker, Ross; Douglas, Marc; Raftery, Martin; Falvey, Eanna; Mathema, PrabhatBackground The Sports Concussion Assessment Tool (SCAT) is recommended to screen for concussion following head impact events in elite sport. The most recent 5th edition (SCAT5) included a ‘rapid neurological screen’ which introduced new subtests examining comprehension, passive neck movement, and diplopia. This study evaluated the additional diagnostic value of these new subtests. Methods A prospective cohort study was performed in the Pro14 elite Rugby Union competition between September 2018 and January 2020. The SCAT5 was administered by the team doctor to players undergoing off-field screening for concussion during a medical room assessment. Sensitivity, specificity, false negatives, and positives were examined for SCAT5 comprehension, passive neck movement, and diplopia subtests. The reference standard was a final diagnosis of concussion, established by serial standardised clinical assessments over 48 h. Results Ninety-three players undergoing off-field screening for concussion were included. Sensitivity and specificity of the comprehension, passive neck movement, and diplopia subtests were 0, 8, 5% and 0, 91, 97%, respectively (concussion prevalence 63%). No players had any abnormality in comprehension. No players had abnormal passive neck movement or diplopia in the absence of abnormalities in other SCAT5 sub-components. Conclusions The new SCAT5 neurological screen subtests are normal in the majority of players undergoing off-field concussion screening and appear to lack diagnostic utility over and above other SCAT5 subtests.
- ItemRestrictedHaemozoin formation(Elsevier, 2008) Egan, Timothy JFormation of malaria pigment or haemozoin is the major route of haem detoxification in the malaria parasite Plasmodium falciparum as well as several other species of haematophagous organisms, including other Plasmodium species, helminth worms such as Schistosoma mansoni and blood-sucking insects such as Rhodnius prolixus. Recent advances in our understanding of the formation of haemozoin, both from new observations that it is formed within lipid bodies in P. falciparum and S. mansoni and biomimetic studies on the formation of its synthetic counterpart -haematin are reviewed. The review also covers methods available for screening compounds for their ability to inhibit -haematin formation.
- ItemOpen AccessHearing loss in the developing world: Evaluating the iPhone mobile device as a screening tool(2014) Peer, Shazia; Fagan, Johannes JBACKGROUND: Developing countries have the world's highest prevalence of hearing loss, and hearing screening programmes are scarce. Mobile devices such as smartphones have potential for audiometric testing. OBJECTIVES: To evaluate the uHear app using an Apple iPhone as a possible hearing screening tool in the developing world, and to determine accuracy of certain hearing thresholds that could prove useful in early detection of hearing loss for high-risk populations in resource-poor communities. METHODS: This was a quasi-experimental study design. Participants recruited from the Otolaryngology Clinic, Groote Schuur Hospital, Cape Town, South Africa, completed a uHear test in three settings - waiting room (WR), quiet room (QR) and soundproof room (SR). Thresholds were compared with formal audiograms. RESULTS: Twenty-five patients were tested (50 ears). The uHear test detected moderate or worse hearing loss (pure-tone average (PTA) >40 dB) accurately with a sensitivity of 100% in all three environments. Specificity was 88% (SR), 73% (QR) and 68% (WR). It was highly accurate in detecting high-frequency hearing loss (2 000, 4 000, 6 000 Hz) in the QR and SR with 'good' and 'very good' kappa values, showing statistical significance (p40 dB). It is highly sensitive for detecting threshold changes at high frequencies, making it reasonably well suited to detect presbycusis and ototoxic hearing loss from HIV, tuberculosis therapy and chemotherapy. Portability and ease of use make it appropriate to use in developing world communities that lack screening programmes.
- ItemOpen AccessHIV-associated tuberculosis: relationship between disease severity and the sensitivity of new sputum-based and urine-based diagnostic assays(BioMed Central Ltd, 2013) Lawn, Stephen; Kerkhoff, Andrew; Vogt, Monica; Wood, RobinBACKGROUND: Reducing mortality from HIV-associated tuberculosis (TB) requires diagnostic tools that are rapid and have high sensitivity among patients with poor prognosis. We determined the relationship between disease severity and the sensitivity of new sputum-based and urine-based diagnostic assays. METHODS: Consecutive ambulatory patients enrolling for antiretroviral treatment in South Africa were screened for TB regardless of symptoms using diagnostic assays prospectively applied to sputum (fluorescence smear microscopy, Xpert MTB/RIF and liquid culture (reference standard)) and retrospectively applied to stored urine samples (Determine TB-LAM and Xpert MTB/RIF). Assay sensitivities were calculated stratified according to pre-defined indices of disease severity: CD4 count, symptom intensity, serum C-reactive protein (CRP), hemoglobin concentration and vital status at 90 days. RESULTS: Sputum culture-positive TB was diagnosed in 15% (89/602) of patients screened and data from 86 patients were analyzed (median CD4 count, 131 cells/muL) including 6 (7%) who died. The sensitivity of sputum microscopy was 26.7% overall and varied relatively little with disease severity. In marked contrast, the sensitivities of urine-based and sputum-based diagnosis using Determine TB-LAM and Xpert MTB/RIF assays were substantially greater in sub-groups with poorer prognosis. Rapid diagnosis from sputum and/or urine samples was possible in >80% of patients in sub-groups with poor prognosis as defined by either CD4 counts <100 cells/muL, advanced symptoms, CRP concentrations >200 mg/L or hemoglobin <8.0 g/dl. Retrospective testing of urine samples with Determine TB-LAM correctly identified all those with TB who died. CONCLUSIONS: The sensitivities of Xpert MTB/RIF and Determine TB-LAM for HIV-associated TB were highest among HIV-infected patients with the most advanced disease and poorest prognostic characteristics. These data provide strong justification for large-scale intervention studies that assess the impact on survival of screening using these new sputum-based and urine-based diagnostic approaches.
- ItemOpen AccessIncidence of cytological abnormalities within 24 months of a normal cervical smear in Soweto, South Africa(2012) Adam, Yasmin; McIntyre, James Alasdair; de Bruyn, GuyBACKGROUND: A screening programme for cervical cancer has been implemented in South Africa (SA) with intervals of 10 years after a normal cytological result. There are no studies that evaluate repeat screening at a shorter interval in SA. OBJECTIVES: (i) To find the incidence of cytological abnormalities on a repeat test after a report of normal cytology or an inadequate Pap smear; and (ii) to explore the factors associated with an abnormal cytology on repeat testing. METHODS: This was a secondary data analysis of a randomised controlled trial of diaphragm, lubricant gel and condoms v. condoms in the prevention of HIV infection. HIV-negative women were recruited between November 2003 and December 2005, with a normal Pap smear at entry. Observation time was from the first Pap smear to the date of the repeat Pap smear. Explanatory variables used were baseline, excepting any new HIV infection. RESULTS: The incidence of cytological abnormalities was 6.48% yearly in women with a previously normal Pap smear and 11.71% yearly in women with an inadequate smear result (p=0.03). The incidence of high-grade squamous intra-epithelial lesions (HSILs) was <0.5%. Factors associated with abnormal cytology were a history of ectopic pregnancy (odds ratio (OR) 9.25; confidence interval (CI) 1.78 - 48.02; p=0.01), number of male partners (OR 1.12; CI 1.03 - 1.22; p=0.01), history of vaginal discharge (OR 13.95; CI 1.18 - 164.47; p=0.04), and incident HIV infection (OR 6.56; CI 1.14 - 38.16; p=0.04). CONCLUSION: The incidence of HSILs is low in the first 2 years after a normal or inadequate Pap smear, even in a setting with a high prevalence of cytological abnormalities.
- ItemOpen AccessPoint-of-care detection of lipoarabinomannan (LAM) in urine for diagnosis of HIV-associated tuberculosis: a state of the art review(BioMed Central Ltd, 2012) Lawn, StephenDetection of Mycobacterium tuberculosis antigens in urine is attractive as a potential means of diagnosing tuberculosis (TB) regardless of the anatomical site of disease. The most promising candidate antigen is the cell wall lipopolysaccharide antigen lipoarabinomannan (LAM), which has been used to develop commercially available enzyme-linked immunosorbent assays. Although highly variable diagnostic accuracy has been observed in different clinical populations, it is now clear that this assay has useful sensitivity for diagnosis of HIV-associated TB in patients with advanced immunodeficiency and low CD4 cell counts. Thus, this assay is particularly useful when selectively used among patients enrolling in antiretroviral treatment services or in HIV-infected patients requiring admission to hospital medical wards. These are the very patients who have the highest mortality risk and who stand to gain the most from rapid diagnosis, permitting immediate initiation of TB treatment. A recently developed low-cost, lateral-flow (urine 'dip-stick') format of the assay provides a result within 30 minutes and is potentially a major step forward as it can be used at the point-of-care, making the possibility of immediate diagnosis and treatment a reality. This paper discusses the likely utility of this point-of-care assay and how it might best be used in combination with other diagnostic assays for TB. The many further research studies that are needed on this assay are described. Consideration is particularly given to potential reasons for the variable specificity observed in existing field evaluations of LAM ELISAs. Whether this might be related to the assay itself or to the challenges associated with study design is discussed.
- ItemOpen AccessPrevalence of rheumatic heart disease in Zambian school children(BioMed Central, 2018-07-03) Schwaninger, Sherri; Musuku, John; Engel, Mark E; Musonda, Patrick; Lungu, Joyce C; Machila, Elizabeth; Mtaja, Agnes; Mulendele, Evans; Kavindele, Dorothy; Spector, Jonathan; Tadmor, Brigitta; Gutierrez, Marcelo M; Van Dam, Joris; Colin, Laurence; Long, Aidan; Fishman, Mark C; Mayosi, Bongani M; Zühlke, Liesl JBackground The large global burden of rheumatic heart disease (RHD) has come to light in recent years following robust epidemiologic studies. As an operational research component of a broad program aimed at primary and secondary prevention of RHD, we sought to determine the current prevalence of RHD in the country’s capital, Lusaka, using a modern imaging-based screening methodology. In addition, we wished to evaluate the practicality of training local radiographers in echocardiography screening methods. Methods Echocardiography was conducted on a random sample of students in 15 schools utilizing a previously validated, abbreviated screening protocol. Through a task-shifting scheme, and in the spirit of capacity-building to enhance local diagnostic and research skills, general radiographers based at Lusaka University Teaching Hospital (UTH) were newly trained to use portable echocardiography devices. Students deemed as screen-positive were referred for comprehensive echocardiography and clinical examination at UTH. Cardiac abnormalities were classified according to standard World Heart Federation criteria. Results Of 1102 students that were consented and screened, 53 students were referred for confirmatory echocardiography. Three students had definite RHD, 10 had borderline RHD, 29 were normal, and 11 students were lost to follow-up. The rates of definite, borderline, and total RHD were 2.7 per 1000, 9.1 per 1000, and 11.8 per 1000, respectively. Anterior mitral valve leaflet thickening and chordal thickening were the most common morphological defects. The pairwise kappa test showed fair agreement between the local radiographers and an echocardiographer quality assurance specialist. Conclusion The prevalence of asymptomatic RHD in urban communities in Zambia is within the range of results reported in other sub-Saharan African countries using the WHF criteria. Task-shifting local radiographers to conduct echocardiography was feasible. The results of this study will be used to inform ongoing efforts in Zambia to control and eventually eliminate RHD. Trial registration The study was registered on clinicaltrials.gov ( #NCT02661763 ).
- ItemOpen AccessRapid microbiological screening for tuberculosis in HIV-positive patients on the first day of acute hospital admission by systematic testing of urine samples using Xpert MTB/RIF: a prospective cohort in South Africa(2015-08-14) Lawn, Stephen D; Kerkhoff, Andrew D; Burton, Rosie; Schutz, Charlotte; van Wyk, Gavin; Vogt, Monica; Pahlana, Pearl; Nicol, Mark P; Meintjes, GraemeAbstract Background Autopsy studies of HIV/AIDS-related hospital deaths in sub-Saharan Africa reveal frequent failure of pre-mortem diagnosis of tuberculosis (TB), which is found in 34–64 % of adult cadavers. We determined the overall prevalence and predictors of TB among consecutive unselected HIV-positive adults requiring acute hospital admission and the comparative diagnostic yield obtained by screening urine and sputum samples obtained on day 1 of admission with Xpert MTB/RIF (Xpert). Methods To determine overall TB prevalence accurately, comprehensive clinical sampling (sputum, urine, blood plus other relevant samples) was done and TB was defined by detection of Mycobacterium tuberculosis in any sample using Xpert and/or mycobacterial liquid culture. To evaluate a rapid screening strategy, we compared the diagnostic yield of Xpert testing sputum samples and urine samples obtained with assistance from a respiratory study nurse in the first 24 h of admission. Results Unselected HIV-positive acute adult new medical admissions (n = 427) who were not receiving TB treatment were enrolled irrespective of clinical presentation or symptom profile. From 2,391 cultures and Xpert tests done (mean, 5.6 tests/patient) on 1,745 samples (mean, 4.1 samples/patient), TB was diagnosed in 139 patients (median CD4 cell count, 80 cells/μL). TB prevalence was very high (32.6 %; 95 % CI, 28.1–37.2 %; 139/427). However, patient symptoms and risk factors were poorly predictive for TB. Overall, ≥1 non-respiratory sample(s) tested positive in 115/139 (83 %) of all TB cases, including positive blood cultures in 41/139 (29.5 %) of TB cases. In the first 24 h of admission, sputum (spot and/or induced samples) and urine were obtainable from 37.0 % and 99.5 % of patients, respectively (P <0.001). From these, the proportions of total TB cases (n = 139) that were diagnosed by Xpert testing sputum, urine or both sputum and urine combined within the first 24 h were 39/139 (28.1 %), 89/139 (64.0 %) and 108/139 (77.7 %) cases, respectively (P <0.001). Conclusions The very high prevalence of active TB and its non-specific presentation strongly suggest the need for routine microbiological screening for TB in all HIV-positive medical admissions in high-burden settings. The incremental diagnostic yield from Xpert testing urine was very high and this strategy might be used to rapidly screen new admissions, especially if sputum is difficult to obtain.
- ItemOpen AccessRapid urine-based screening for tuberculosis to reduce AIDS-related mortality in hospitalized patients in Africa (the STAMP trial): study protocol for a randomised controlled trial(2016) Gupta-Wright, Ankur; Fielding, Katherine L; van Oosterhout, Joep J; Wilson, Douglas K; Corbett, Elizabeth L; Flach, Clare; Reddy, Krishna P; Walensky, Rochelle P; Peters, Jurgens A; Alufandika-Moyo, Melanie; Lawn, Stephen DAbstract Background HIV-associated tuberculosis (TB) co-infection remains an enormous burden to international public health. Post-mortem studies have highlighted the high proportion of HIV-positive adults admitted to hospital with TB. Determine TB-LAM and Xpert MTB/RIF assays can substantially increase diagnostic yield of TB within one day of hospital admission. However, it remains unclear if this approach can impact clinical outcomes. The STAMP trial aims to test the hypothesis that the implementation a urine-based screening strategy for TB can reduce all cause-mortality among HIV-positive patients admitted to hospital when compared to current, sputum-based screening. Methods The trial is a pragmatic, individually randomised, multi-country (Malawi and South Africa) clinical trial with two study arms (1:1 recruitment). Unselected HIV-positive patients admitted to medical wards, irrespective of presentation, meeting the inclusion criteria and giving consent will be randomized to screening for TB using either: (i) ‘standard of care’- testing of sputum using the Xpert MTB/RIF assay (Xpert) or (ii) ‘intervention’- testing of sputum using Xpert and testing of urine using (a) Determine TB-LAM lateral-flow assay and (b) Xpert following concentration of urine by centrifugation. Patients will be excluded if they have received TB treatment in the previous 12 months, if they have received isoniazid preventive therapy in the last 6 months, if they are aged <18 years or they live outside the pre-specified geographical area. Results will be provided to the responsible medical team as soon as available to inform decisions regarding TB treatment. Both the study and routine medical team will be masked to study arm allocation. 1300 patients will be enrolled per arm (equal numbers at the two trial sites). The primary endpoint is all-cause mortality at 56 days. An economic analysis will be conducted to project long-term outcomes for shorter-term trial data, including cost-effectiveness. Discussion This pragmatic trial assesses an intervention to reduce the high mortality caused by HIV-associated TB, which could feasibly be scaled up in high-burden settings if shown to be efficacious and cost-effective. We discuss the challenges of designing a trial to assess the impact on mortality of laboratory-based TB screening interventions given frequent initiation of empirical treatment and a failure of several previous clinical trials to demonstrate an impact on clinical outcomes. We also elaborate on the practical and ethical issues of ‘testing a test’ in general. Trial registration ISRCTN Registry (ISRCTN71603869) prospectively registered 08 May 2015; the South African National Controlled Trials Registry (DOH-27-1015-5185) prospectively registered October 2015.
- ItemOpen AccessReasons for poor follow-up of diabetic retinopathy patients after screening in Tanzania: a cross-sectional study(2016) Mtuya, Christina; Cleland, Charles R; Philippin, Heiko; Paulo, Kidayi; Njau, Bernard; Makupa, William U; Hall, Claudette; Hall, Anthony; Courtright, Paul; Mushi, DeclareAbstract Background Diabetes is an emerging public health problem in sub-Saharan Africa. Diabetic retinopathy is the commonest microvascular complication of diabetes and is a leading cause of blindness, mainly in adults of working age. Follow-up is crucial to the effective management of diabetic retinopathy, however, follow-up rates are often poor in sub-Saharan Africa. The aim of this study was to assess the proportion of patients not presenting for follow-up and the reasons for poor follow-up of diabetic patients after screening for retinopathy in Kilimanjaro Region of Tanzania. Methods All diabetic patients referred to a tertiary ophthalmology hospital after screening for retinopathy in 2012 were eligible for inclusion in the study. A randomly selected group of patients from the community-based diabetic retinopathy screening register were identified; among this group, follow-up was assessed. Interviews were conducted within this group to inform on the reasons for poor follow-up. Results Among the 203 patients interviewed in the study 50 patients (24.6 %) attended the recommended referral appointment and 153 (75.4 %) did not. Financial reasons were self-reported by 35.3 % of those who did not attend the follow-up appointment as the reason for non-attendance. Multiple logistic regression analysis showed that the patient report of the clarity of the referral process (p = 0.014) and the patient report of whether a healthcare worker told the patient that diabetic retinopathy could be treated (p = 0.005) were independently associated with attendance at a follow-up appointment. Income per month was not associated with attendance at a follow-up appointment on multivariate analysis. Conclusions Financial factors are commonly cited as the reason for non-compliance with follow-up recommendations. However, the reasons for poor compliance are likely to be more complicated. This study highlights the importance of health system factors. Improving the clarity of the referral process and frequent reminders to patients that diabetic retinopathy can be treated are practical strategies that should be incorporated into screening programmes to increase attendance at subsequent follow-up appointments. The results from this study are applicable to other screening programmes as well as those for diabetic retinopathy.
- ItemOpen AccessReporting and handling of missing data in predictive research for prevalent undiagnosed type 2 diabetes mellitus: a systematic review(BioMed Central Ltd, 2015) Masconi, Katya L; Matsha, Tandi; Echouffo-Tcheugui, Justin; Erasmus, Rajiv; Kengne, AndreMissing values are common in health research and omitting participants with missing data often leads to loss of statistical power, biased estimates and, consequently, inaccurate inferences. We critically reviewed the challenges posed by missing data in medical research and approaches to address them. To achieve this more efficiently, these issues were analyzed and illustrated through a systematic review on the reporting of missing data and imputation methods (prediction of missing values through relationships within and between variables) undertaken in risk prediction studies of undiagnosed diabetes. Prevalent diabetes risk models were selected based on a recent comprehensive systematic review, supplemented by an updated search of English-language studies published between 1997 and 2014. Reporting of missing data has been limited in studies of prevalent diabetes prediction. Of the 48 articles identified, 62.5% (n=30) did not report any information on missing data or handling techniques. In 21 (43.8%) studies, researchers opted out of imputation, completing case-wise deletion of participants missing any predictor values. Although imputation methods are encouraged to handle missing data and ensure the accuracy of inferences, this has seldom been the case in studies of diabetes risk prediction. Hence, we elaborated on the various types and patterns of missing data, the limitations of case-wise deletion and state-of the-art methods of imputations and their challenges. This review highlights the inexperience or disregard of investigators of the effect of missing data in risk prediction research. Formal guidelines may enhance the reporting and appropriate handling of missing data in scientific journals.
- ItemOpen AccessA study to evaluate immunodiagnostic tests for tuberculosis infection and determinants of TB infection in a population of health care workers in the Western Cape of South Africa(2015) Adams, Shahieda; Dheda, Keertan; Ehrlich, RodneyBackground: Health care workers are at increased risk of acquiring latent tuberculosis infection (LTBI). The emergence of interferon - gamma release assays (IGRAs) for the diagnosis of LTBI, presents an opportunity for improved estimation of TB infection prevalence and incidence. Their utility in settings with high background prevalence TB and HIV infection is unknown. Major aims of the study were to: * Evaluate the prevalence and factors associated with TB infection using both tuberculin skin test (TST) and IGRA assays in a sample of health care workers. * Evaluate change in interval test response over one year to determine annual risk of infection and determinants associated with test conversion. Methods: Participants completed a questionnaire on occupational and environmental characteristics including a TB symptom screen and underwent chest radiograph and rapid HIV test. Three tests for latent TB infection were administered: TST, QuantiFERON - TB Gold In - Tube (QFT - GIT) and a T - SPOT.TB test. All tests were repeated one year later. Results: The prevalence of TB infection at baseline was 84%, 65% and 60% as measured by TST, QFT - GIT and T - SPOT.TB. There was only fair agreement between TST and IGRAs. HIV positive status was significantly associated with having a TST negative / T - SPOT.TB positive discordant test response (OR=4.72). TST had superior sensitivity than IGRAs for the diagnosis of LTBI. In primary level staff a positive TST outcome, was negatively associated with HIV positive status (OR=0.41). Long employment duration was positively associated with TST (OR=4.17) and QFT - GIT (OR= 2.42) positivity. Involvement in sputum collection (OR=3.25) and home - based care of TB patients (OR= 4.14) was associated with a positive IGRA test. The conversion rate for TST and IGRAs was 38% and 22%, respectively. Reversion rates ranged from 1 % - 16 % and was lowest for TST. Factors associated with conversion (for IGRAs) included employment sector, counselling of TB patients and a baseline positive TST. Conclusion: The annual rate of TB infection was very high pointing to occupational exposure as a contributory factor. TST had superior sensitivity than IGRAs for LTBI diagnosis but poor uptake on serial testing. IGRAs had excellent uptake but its clinical utility was negatively influenced by high rates of reversion.
- ItemOpen AccessThe performance of the World Rugby Head Injury Assessment Screening Tool: a diagnostic accuracy study(2020-01-09) Fuller, G. W; Tucker, R.; Starling, L.; Falvey, E.; Douglas, M.; Raftery, M.Abstract Background Off-field screening tools, such as the Sports Concussion Assessment Tool (SCAT), have been recommended to identify possible concussion following a head impact where the consequences are unclear. However, real-life performance, and diagnostic accuracy of constituent sub-tests, have not been well characterized. Methods A retrospective cohort study was performed in elite Rugby Union competitions between September 2015 and June 2018. The study population comprised consecutive players identified with a head impact event undergoing off-field assessments with the World Rugby Head Injury Assessment (HIA01) screening tool, an abridged version of the SCAT3. Off-field screening performance was investigated by evaluating real-life removal-from-play outcomes and determining the theoretical diagnostic accuracy of the HIA01 tool, and individual sub-tests, if player-specific baseline or normative sub-test thresholds were strictly applied. The reference standard was clinically diagnosed concussion determined by serial medical assessments. Results One thousand one hundred eighteen head impacts events requiring off-field assessments were identified, resulting in 448 concussions. Real-life removal-from-play decisions demonstrated a sensitivity of 76.8% (95% CI 72.6–80.6) and a specificity of 86.6% (95% CI 83.7–89.1) for concussion (AUROC 0.82, 95% CI 0.79–0.84). Theoretical HIA01 tool performance worsened if pre-season baseline values (sensitivity 89.6%, specificity 33.9%, AUROC 0.62, p < 0.01) or normative thresholds (sensitivity 80.4%, specificity 69.0%, AUROC 0.75, p < 0.01) were strictly applied. Symptoms and clinical signs were the HIA01 screening tool sub-tests most predictive for concussion; with immediate memory and tandem gait providing little additional diagnostic value. Conclusions These findings support expert recommendations that clinical judgement should be used in the assessment of athletes following head impact events. Substitution of the tandem gait and 5-word immediate memory sub-tests with alternative modes could potentially improve screening tool performance.
- ItemOpen AccessUtility of interferon-gamma ELISPOT assay responses in highly tuberculosis-exposed patients with advanced HIV infection in South Africa(Biomed Central Ltd, 2007) Lawn, Stephen; Bangani, Nonzwakazi; Vogt, Monica; Bekker, Linda-Gail; Badri, Motasim; Ntobongwana, Marjorie; Dockrell, Hazel; Wilkinson, Robert; Wood, RobinBACKGROUND:Interferon-gamma (IFN-gamma) ELISPOT assays incorporating Mycobacterium tuberculosis-specific antigens are useful in the diagnosis of tuberculosis (TB) or latent infection. However, their utility in patients with advanced HIV is unknown. We studied determinants of ELISPOT responses among patients with advanced HIV infection (but without active TB) living in a South African community with very high TB notification rates. METHODS: IFN-gamma responses to ESAT-6 and CFP-10 in overnight ELISPOT assays and in 7-day whole blood assays (WBA) were compared in HIV-infected patients (HIV+, n = 40) and healthy HIV-negative controls (HIV-, n = 30) without active TB. Tuberculin skin tests (TSTs) were also done. RESULTS: ELISPOTs, WBAs and TSTs were each positive in >70% of HIV- controls, reflecting very high community exposure to M. tuberculosis. Among HIV+ patients, quantitative WBA responses and TSTs (but not the proportion of positive ELISPOT responses) were significantly impaired in those with CD4 cell counts <100 cells/mul compared to those with higher counts. In contrast, ELISPOT responses (but not WBA or TST) were strongly related to history of TB treatment; a much lower proportion of HIV+ patients who had recently completed treatment for TB (n = 19) had positive responses compared to those who had not been treated (11% versus 62%, respectively; P < 0.001). Multivariate analysis confirmed that ELISPOT responses had a strong inverse association with a history of recent TB treatment (adjusted OR = 0.06, 95%CI = 0.10-0.40, P < 0.01) and that they were independent of CD4 cell count and viral load. Among HIV+ individuals who had not received TB treatment both the magnitude and proportion of positive ELISPOT responses (but not TST or WBA) were similar to those of HIV-negative controls. CONCLUSION: The proportion of positive ELISPOT responses in patients with advanced HIV infection was independent of CD4 cell count but had a strong inverse association with history of TB treatment. This concurs with the previously documented low TB risk among patients in this cohort with a history of recent treatment for TB. These data suggest ELISPOT assays may be useful for patient assessment and as an immuno-epidemiological research tool among patients with advanced HIV and warrant larger scale prospective evaluation.
- ItemOpen AccessValidation of the 10-item Centre for Epidemiological Studies Depression Scale (CES-D-10) in Zulu, Xhosa and Afrikaans populations in South Africa(2017) Baron, Emily Claire; Davies, Thandi; Lund, CrickAbstract Background The 10-item Centre for Epidemiological Studies Depression Scale (CES-D-10) is a depression screening tool that has been used in the South African National Income Dynamics Study (NIDS), a national household panel study. This screening tool has not yet been validated in South Africa. This study aimed to establish the reliability and validity of the CES-D-10 in Zulu, Xhosa and Afrikaans. The CES-D-10’s psychometric properties were also compared to the Patient Health Questionnaire (PHQ-9), a depression screening tool already validated in South Africa. Methods Stratified random samples of Xhosa, Afrikaans and Zulu-speaking participants aged 15 years or older (N = 944) were recruited from Cape Town Metro and Ethekwini districts. Face-to-face interviews included socio-demographic questions, the CES-D-10, Patient Health Questionnaire (PHQ-9), and WHO Disability Assessment Schedule 2.0 (WHODAS). Major depression was determined using the Mini International Neuropsychiatric Interview. All instruments were translated and back-translated to English. Construct validity was examined using exploratory factor analysis with varimax rotation. Receiver Operating Characteristics (ROC) curves were used to investigate the CES-D-10 and PHQ-9’s criterion validity, and compared using the DeLong method. Results Overall, 6.6, 18.0 and 6.9% of the Zulu, Afrikaans and Xhosa samples were diagnosed with depression, respectively. The CES-D-10 had acceptable internal consistency across samples (α = 0.69–0.89), and adequate concurrent validity, when compared to the PHQ-9 and WHODAS. The CES-D-10 area under the Receiver Operator Characteristic curve was good to excellent: 0.81 (95% CI 0.71–0.90) for Zulu, 0.93 (95% CI 0.90–0.96) for Afrikaans, and 0.94 (95% CI 0.89–0.99) for Xhosa. A cut-off of 12, 11 and 13 for Zulu, Afrikaans and Xhosa, respectively, generated the most balanced sensitivity, specificity and positive predictive value (Zulu: 71.4, 72.6% and 16.1%; Afrikaans: 84.6%, 84.0%, 53.7%; Xhosa: 81.0%, 95.0%, 54.8%). These were slightly higher than those generated for the PHQ-9. The CES-D-10 and PHQ-9 otherwise performed similarly across samples. Conclusions The CES-D-10 is a valid, reliable screening tool for depression in Zulu, Xhosa and coloured Afrikaans populations.
- ItemOpen AccessValidation of the 10-item Centre for Epidemiological Studies Depression Scale (CES-D-10) in Zulu, Xhosa and Afrikaans populations in South Africa(BioMed Central, 2017-01-09) Baron, Emily C; Davies, Thandi; Lund, CrickBackground: The 10-item Centre for Epidemiological Studies Depression Scale (CES-D-10) is a depression screening tool that has been used in the South African National Income Dynamics Study (NIDS), a national household panel study. This screening tool has not yet been validated in South Africa. This study aimed to establish the reliability and validity of the CES-D-10 in Zulu, Xhosa and Afrikaans. The CES-D-10’s psychometric properties were also compared to the Patient Health Questionnaire (PHQ-9), a depression screening tool already validated in South Africa. Methods: Stratified random samples of Xhosa, Afrikaans and Zulu-speaking participants aged 15 years or older (N = 944) were recruited from Cape Town Metro and Ethekwini districts. Face-to-face interviews included socio-demographic questions, the CES-D-10, Patient Health Questionnaire (PHQ-9), and WHO Disability Assessment Schedule 2.0 (WHODAS). Major depression was determined using the Mini International Neuropsychiatric Interview. All instruments were translated and back-translated to English. Construct validity was examined using exploratory factor analysis with varimax rotation. Receiver Operating Characteristics (ROC) curves were used to investigate the CES-D-10 and PHQ-9’s criterion validity, and compared using the DeLong method. Results: Overall, 6.6, 18.0 and 6.9% of the Zulu, Afrikaans and Xhosa samples were diagnosed with depression, respectively. The CES-D-10 had acceptable internal consistency across samples (α = 0.69–0.89), and adequate concurrent validity, when compared to the PHQ-9 and WHODAS. The CES-D-10 area under the Receiver Operator Characteristic curve was good to excellent: 0.81 (95% CI 0.71–0.90) for Zulu, 0.93 (95% CI 0.90–0.96) for Afrikaans, and 0. 94 (95% CI 0.89–0.99) for Xhosa. A cut-off of 12, 11 and 13 for Zulu, Afrikaans and Xhosa, respectively, generated the most balanced sensitivity, specificity and positive predictive value (Zulu: 71.4, 72.6% and 16.1%; Afrikaans: 84.6%, 84.0%, 53.7%; Xhosa: 81.0%, 95.0%, 54.8%). These were slightly higher than those generated for the PHQ-9. The CES-D-10 and PHQ-9 otherwise performed similarly across samples. Conclusions: The CES-D-10 is a valid, reliable screening tool for depression in Zulu, Xhosa and coloured Afrikaans populations.