Factors associated with screening failure and study withdrawal in multidrug-resistant TB

SETTING: Multidrug-resistant TB (MDR-TB) clinical trial in Lima, Peru and Cape Town, South Africa.OBJECTIVE: To identify baseline factors associated with screening failure and study withdrawal in an MDR-TB clinical trial.DESIGN: We screened patients for a randomized, blinded, Phase II trial which assessed culture conversion over the first 6 months of treatment with varying doses of levofloxacin plus an optimized background regimen (ClinicalTrials.gov: NCT01918397). We identified factors for screening failure and study withdrawal using Poisson regression to calculate prevalence ratios and Cox proportional hazard regression to calculate hazard ratios. We adjusted for factors with P < 0.2.RESULTS: Of the 255 patients screened, 144 (56.5%) failed screening. The most common reason for screening failure was an unsuitable resistance profile on sputum-based molecular susceptibility testing (n = 105, 72.9%). No significant baseline predictors of screening failure were identified in the multivariable model. Of the 111 who were enrolled, 33 (30%) failed to complete treatment, mostly for non-adherence and consent withdrawal. No baseline factors predicted study withdrawal in the multivariable model.CONCLUSION: No baseline factors were independently associated with either screening failure or study withdrawal in this secondary analysis of a MDR-TB clinical trial.

Point of care HbA1c level for diabetes mellitus management and its accuracy among tuberculosis patients: a study in four countries

BACKGROUND

Diabetes mellitus (DM) is common among tuberculosis (TB) patients and often undiagnosed or poorly controlled. We compared point of care (POC) with laboratory glycated haemoglobin (HbA_1c) testing among newly diagnosed TB patients to assess POC test accuracy, safety and acceptability in settings in which immediate access to DM services may be difficult.

METHODS

We measured POC and accredited laboratory HbA_1c (using high-performance liquid chromatography) in 1942 TB patients aged 18 years recruited from Peru, Romania, Indonesia and South Africa. We calculated overall agreement and individual variation (mean ± 2 standard deviations) stratified by country, age, sex, body mass index (BMI), HbA_1c level and comorbidities (anaemia, human immunodeficiency virus [HIV]). We used an error grid approach to identify disagreement that could raise significant concerns.

RESULTS

Overall mean POC HbA_1c values were modestly higher than laboratory HbA_1c levels by 0.1% units (95%CI 0.1-0.2); however, there was a substantial discrepancy for those with severe anaemia (1.1% HbA_1c, 95%CI 0.7-1.5). For 89.6% of 1942 patients, both values indicated the same DM status (no DM, HbA_1c <6.5%) or had acceptable deviation (relative difference <6%). Individual agreement was variable, with POC values up to 1.8% units higher or 1.6% lower. For a minority, use of POC HbA_1c alone could result in error leading to potential overtreatment (n = 40, 2.1%) or undertreatment (n = 1, 0.1%). The remainder had moderate disagreement, which was less likely to influence clinical decisions.

CONCLUSION

POC HbA_1c is pragmatic and sufficiently accurate to screen for hyperglycaemia and DM risk among TB patients.

Diabetes and poor tuberculosis treatment outcomes: issues and implications in data interpretation and analysis

Tuberculosis (TB) remains one of the 10 leading causes of death worldwide, especially in low- and middle-income countries. We conducted a systematic review and meta-analysis including 88 studies examining the association between diabetes mellitus (DM) and TB treatment outcomes. However, we found several common methodological problems among them, including inappropriate adjustments for confounding factors, not using optimal statistical methods for 'time to event' data, misclassification in exposure (DM) and outcomes (TB treatment outcomes) due to study design and non-standardisation of definitions, misunderstanding of basic study design concept, standardisation of TB treatment outcomes and quality control of publications. Many of these problems would apply more broadly to other 'risk factors' for poor TB treatment outcomes. These issues need to be addressed and resolved to improve the quality of the studies and provide more accurate results for policy makers in the future to tackle the burden of TB.