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.