A comment on the importance of numerical evaluation of analytic solutions involving approximations

An analytic solution proposed by Senn (1) for removing the effects of covariate imbalance in controlled clinical trials was subjected to Monte Carlo evaluation. For practical applications of his derivation, Senn proposed substitution of sample statistics for parameters of the bivariate normal model. Unfortunately, that substitution produces severe distortion in the size of tests of significance for treatment effects when covariate imbalance is present. Numerical-verification of proposed substitutions into analytic models is recommended as a prudent approach.     

Indirect comparison of bronchial thermoplasty versus omalizumab for uncontrolled severe asthma

Objective: Bronchial thermoplasty (BT) as an add-on therapy for uncontrolled severe asthma is an alternative to biologic therapies like omalizumab (OM). We conducted an indirect treatment comparison (ITC) to appraise comparative effectiveness of BT and OM. Methods: A systematic literature review identified relevant randomized controlled trials. The ITC followed accepted methodology. Results: The ITC comprised a sham-controlled trial of BT (AIR2) and two placebo-controlled trials of OM (INNOVATE; EXTRA). Comparing the BT post-treatment period to ongoing treatment with OM, showed no significant differences in the rate ratios (RRs) for severe exacerbations (RR of BT versus OM = 0.91 [95% CI: 0.64, 1.30]; p = 0.62) or hospitalizations (RR = 0.57 [95% CI: 0.17, 1.86]; p = 0.53); emergency department visits were significantly reduced by 75% with BT (RR = 0.25 [95% CI: 0.07, 0.91]; p = 0.04); the proportions of patients with clinically meaningful response on the asthma quality-of-life questionnaire were comparable (RR = 1.06 [95% CI: 0.86, 1.34]; p = 0.59). The RR for exacerbations statistically favours OM over the total study period in AIR2 (RR = 1.50 [95% CI: 1.11, 2.02]; p = 0.009) likely reflecting a transient increase in events during the BT peri-treatment period. Conclusions: The ITC should be interpreted cautiously considering the differences between patient populations in the included trials. However, based on the analysis, BT compares well with a potentially more costly pharmacotherapy for asthma. Clinicians evaluating the relative merits of using these treatments should consider the totality of evidence and patient preferences to make an informed decision.     

Improving the reliability and reporting of genetic association studies

Genetic association studies, in particular candidate gene studies, have a long history of initially promising findings which subsequently produce a confusing mixture of replications, partial replications and non-replications. Drug and Alcohol Dependence is receiving an increasing number of submissions of genetic association studies. Here we discuss the journal's approach to considering such papers, in order to encourage credible and balanced reports which will contribute positively to the field. Recently, the STrengthening the REporting of Genetic Association studies (STREGA) initiative has provided guidelines which serve to enhance transparency. We strongly encourage authors considering submitting a genetic association study to the journal to follow these guidelines.