Browsing by Author "Cobelens, Frank"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Feasibility and Operational Performance of Tuberculosis Detection by Loop-Mediated Isothermal Amplification Platform in Decentralized Settings: Results from a Multicenter Study
    (Journal of Clinical Microbiology, 2016) Gray, Christen M.; Katamba, Achilles; Narang, Pratibha; Giraldo, Jorge; Zamudio, Carlos; Joloba, Moses; Narang, Rahul; Paramasivan, C. N.; Hillemann, Doris; Nabeta, Pamela; Amisano, Danielle; Alland, David; Cobelens, Frank; Boehme, Catharina C.
    Currently available nucleic acid amplification platforms for tuberculosis (TB) detection are not designed to be simple or inexpensive enough to implement in decentralized settings in countries with a high burden of disease. The loop-mediated isothermal amplification platform (LAMP) may change this. We conducted a study in adults with symptoms suggestive of TB in India, Uganda, and Peru to establish the feasibility of using TB-LAMP (Eiken Chemical Co.) in microscopy laboratories compared with using smear microscopy against a reference standard of solid and liquid cultures. Operational characteristics were evaluated as well. A total of 1,777 participants met the eligibility criteria and were included for analysis. Overall, TB-LAMP sensitivities among culture-positive samples were 97.2% (243/250; 95% confidence interval [CI], 94.3% to 98.2%) and 62.0% (88/142; 95% CI, 53.5% to 70.0%) for smear-positive and smear-negative TB, respectively, but varied widely by country and operator. Specificities ranged from 94.5% (446/472; 95% CI, 92.0% to 96.4%) to 98.0% (350/357; 95% CI, 96.0% to 99.2%) by country. A root cause analysis identified high temperatures, high humidity, and/or low reaction volumes as possible causes for false-positive results, as they may result in nonspecific amplification. The study was repeated in India with training focused on vulnerable steps and an updated protocol; 580 participants were included for analysis. Specificity in the repeat trial was 96.6% (515/533; 95% CI, 94.7% to 97.9%). To achieve acceptable performance of LAMP at the microscopy center level, significant training and infrastructure requirements are necessary.
  • Thumbnail Image
    Item
    High Rates of Pre-exposure Prophylaxis Eligibility and Associated HIV Incidence in a Population With a Generalized HIV Epidemic in Rakai, Uganda
    (Journal of Acquired Immune Deficiency Syndromes, 2022) Ssempijja, Victor; Nakigozi, Gertrude; Ssekubugu, Robert; Kagaayi, Joseph; Kigozi, Godfrey; Nalugoda, Fred; Nantume, Betty; Batte, James; Kigozi, Grace; Nakawooya, Hadijja; Serwadda, David; Cobelens, Frank; Reynolds, Steven J.
    The utility of using pre-exposure prophylaxis (PrEP) eligibility assessments to identify eligibility in general populations has not been well studied in sub-Saharan Africa. We used the Rakai Community Cohort Study to conduct a cross-sectional analysis to estimate PrEP eligibility and a cohort analysis to estimate HIV incidence associated with PrEP eligibility. Based on Uganda's national PrEP eligibility tool, we defined eligibility as reporting at least one of the following HIV risks in the past 12 months: sexual intercourse with more than one partner of unknown HIV status; nonmarital sex act without a condom; sex engagement in exchange for money, goods, or services; or experiencing genital ulcers. We used log-binomial and modified Poisson models to estimate prevalence ratios for PrEP eligibility and HIV incidence, respectively.
  • Thumbnail Image
    Item
    Implementation of Xpert MTB/RIF in Uganda: Missed Opportunities to Improve Diagnosis of Tuberculosis
    (Oxford University Press, 2016) Hanrahan, Colleen F.; Haguma, Priscilla; Ochom, Emmanuel; Kinera, Irene; Cobelens, Frank; Cattamanchi, Adithya; Davis, Luke; Katamba, Achilles; Dowdy, David
    The effect of Xpert MTB/RIF (Xpert) scale-up on patient outcomes in low-income settings with a high tuberculosis (TB) burden has not been established. We sought to characterize the effectiveness of Xpert as implemented across different levels of the healthcare system in Uganda. Methods. We reviewed laboratory records from 2012 to 2014 at 18 health facilities throughout Uganda. In 8 facilities, Xpert had been implemented onsite since 2012, and in 10 sites Xpert was available as an offsite referral test from another facility. We describe Xpert testing volumes by facility, Xpert and smear microscopy results, and downtime due to malfunction and cartridge stockouts.We compare TB treatment initiation as well as time to treatment between facilities implementing Xpert and those that did not. Results. The median number of Xpert assays run at implementing facilities was 25/month (interquartile range [IQR], 10–63), amounting to 8% of total capacity. Among 1251 assays run for a new TB diagnosis, 19% were positive. Among 1899 patients with smear-negative presumptive TB, the proportion starting TB treatment was similar between Xpert facilities (11%; 95% confidence interval [CI], 9%–13%) and non-Xpert facilities (9%; 95% CI, 8%–11%; P = .325). In Xpert facilities, a positive Xpert preceded TB treatment initiation in only 12 of 70 (17%) smear-negative patients initiated on treatment. Conclusions. Xpert was underutilized in Uganda and did not significantly increase the number of patients starting treatment for TB. Greater attention must be paid to appropriate implementation of novel diagnostic tests for TB if these new tools are to impact patient important outcomes.
  • Thumbnail Image
    Item
    Long Delays and Missed Opportunities in Diagnosing Smear-Positive Pulmonary Tuberculosis in Kampala, Uganda: A Cross-Sectional Study
    (PLOS one, 2010) Sendagire, Ibrahim; Loeff, Maarten Schim Van der; Mubiru, Mesach; Konde-Lule, Joseph; Cobelens, Frank
    Early detection and treatment of tuberculosis cases are the hallmark of successful tuberculosis control. We conducted a cross-sectional study at public primary health facilities in Kampala city, Uganda to quantify diagnostic delay among pulmonary tuberculosis (PTB) patients, assess associated factors, and describe trajectories of patients' health care seeking. Semi-structured interviews with new smear-positive PTB patients (≥15 years) registered for treatment. Between April 2007 and April 2008, 253 patients were studied. The median total delay was 8 weeks (IQR 4–12), median patient delay was 4 weeks (inter-quartile range [IQR] 1–8) and median health service delay was 4 weeks (IQR 2–8). Long total delay (>14 weeks) was observed for 61/253 (24.1%) of patients, long health service delay (>6 weeks) for 71/242 (29.3%) and long patient delay (>8 weeks) for 47/242 (19.4%). Patients who knew that TB was curable were less likely to have long total delay (adjusted Odds Ratio [aOR] 0.28; 95%CI 0.11–0.73) and long patient delay (aOR 0.36; 95%CI 0.13–0.97). Being female (aOR 1.98; 95%CI 1.06–3.71), staying for more than 5 years at current residence (aOR 2.24 95%CI 1.18–4.27) and having been tested for HIV before (aOR 3.72; 95%CI 1.42–9.75) was associated with long health service delay. Health service delay contributed 50% of the total delay. Ninety-one percent (231) of patients had visited one or more health care providers before they were diagnosed, for an average (median) of 4 visits (range 1–30). All but four patients had systemic symptoms by the time the diagnosis of TB was made. Diagnostic delay among tuberculosis patients in Kampala is common and long. This reflects patients waiting too long before seeking care and health services waiting until systemic symptoms are present before examining sputum smears; this results in missed opportunities for diagnosis.
  • Thumbnail Image
    Item
    Low HIV testing rates among tuberculosis patients in Kampala, Uganda
    (BMC Public Health, 2010) Sendagire, Ibrahim; Schreuder, Imke; Mubiru, Mesach; Cobelens, Frank; Konde-Lule, Joseph
    HIV testing among tuberculosis patients is critical in improving morbidity and mortality as those found to be HIV positive will be offered a continuum of care including ART if indicated. We conducted a cross-sectional study in three Kampala City primary care clinics: to assess the level of HIV test uptake among newly diagnosed pulmonary tuberculosis (PTB) patients; to assess patient and health worker factors associated with HIV test uptake; and to determine factors associated with HIV test uptake at the primary care clinics