Modelling cumulative exposure for inference about drug effects in observational studies.

PURPOSE: To demonstrate a modelling approach that controls for time-invariant allocation bias in estimation of associations of outcome with drug exposure. METHODS: We show that in a model that includes terms for both ever-exposure versus never-exposure and cumulative exposure, the parameter for ever-exposure represents the effect of time-invariant allocation bias, and the parameter for cumulative exposure represents the effect of the drug after adjustment for this unmeasured confounding. This assumes no stepwise effect of the drug on the event rate, no reverse causation, and no unmeasured time-varying confounders. We demonstrated this by modelling the effect of statins on cardiovascular disease, for which the true effect has been well characterised in randomised trials, using time-updated Cox regression models in a national cohort of Type 2 diabetes patients. RESULTS: The crude hazard ratio associated with ever-use of statins was 1.13 in a standard cohort analysis comparing exposed with unexposed person-time intervals. When ever-never use and cumulative exposure are modelled jointly, the effect of statins can be estimated from the cumulative exposure parameter (hazard ratio 0.97 per year of exposure, 95% CI 0.97 to 0.98). The ever-exposed term (hazard ratio 1.20, 1.16 to 1.23) in this model can be interpreted as estimating the allocation bias. CONCLUSIONS: Where stepwise effects on the risk of adverse events are unlikely, as for instance for effects on risk of cancer, joint modelling of ever-never and cumulative exposure can be used to study the effects of multiple drugs and to distinguish causal effects from confounding by allocation.

Computerized occlusion rating of embolized ruptured intracranial aneurysms: relation to intra- and postinterventional aneurysm rehemorrhage.

Endovascular coil occlusion of ruptured cerebral aneurysms has a higher rate of rebleeding compared to surgical clipping. Initial aneurysm coil occlusion rate (OR) is the strongest available predictor of aneurysm rebleeding. Standard clinical subjective occlusion rating (SOR) is limited by subjective bias. Therefore, computerized occlusion rating (COR) was introduced. Its superiority was established for experimental and human aneurysms. In the present clinical study, we aimed to evaluate COR as a risk factor for postprocedural reruptures (PPRs) and intraprocedural reruptures (IPRs). In our series of 249 consecutive patients treated in our institution, we observed 7 (2.8%) cases with IPR and 7 (2.8%) cases with PPR. These patients were analyzed in the present study. Mean COR value was 85% (range 71-96%). In 12 (85.7%) cases, COR was lower than SOR. In aneurysms with a COR of 95% or higher, no PPR occurred. All patients with IPR harbored multiple aneurysms. In -conclusion, our data showed a distinct tendency of potentially dangerous overestimations when using SOR compared to the objectively measured COR values. IPR was always associated with multiple aneurysms.

Dipeptidyl peptidase-1 inhibition in patients hospitalised with COVID-19: a multicentre, double-blind, randomised, parallel-group, placebo-controlled trial.

BACKGROUND: Neutrophil serine proteases are involved in the pathogenesis of COVID-19 and increased serine protease activity has been reported in severe and fatal infection. We investigated whether brensocatib, an inhibitor of dipeptidyl peptidase-1 (DPP-1; an enzyme responsible for the activation of neutrophil serine proteases), would improve outcomes in patients hospitalised with COVID-19. METHODS: In a multicentre, double-blind, randomised, parallel-group, placebo-controlled trial, across 14 hospitals in the UK, patients aged 16 years and older who were hospitalised with COVID-19 and had at least one risk factor for severe disease were randomly assigned 1:1, within 96 h of hospital admission, to once-daily brensocatib 25 mg or placebo orally for 28 days. Patients were randomly assigned via a central web-based randomisation system (TruST). Randomisation was stratified by site and age (65 years or ≥65 years), and within each stratum, blocks were of random sizes of two, four, or six patients. Participants in both groups continued to receive other therapies required to manage their condition. Participants, study staff, and investigators were masked to the study assignment. The primary outcome was the 7-point WHO ordinal scale for clinical status at day 29 after random assignment. The intention-to-treat population included all patients who were randomly assigned and met the enrolment criteria. The safety population included all participants who received at least one dose of study medication. This study was registered with the ISRCTN registry, ISRCTN30564012. FINDINGS: Between June 5, 2020, and Jan 25, 2021, 406 patients were randomly assigned to brensocatib or placebo; 192 (47·3%) to the brensocatib group and 214 (52·7%) to the placebo group. Two participants were excluded after being randomly assigned in the brensocatib group (214 patients included in the placebo group and 190 included in the brensocatib group in the intention-to-treat population). Primary outcome data was unavailable for six patients (three in the brensocatib group and three in the placebo group). Patients in the brensocatib group had worse clinical status at day 29 after being randomly assigned than those in the placebo group (adjusted odds ratio 0·72 [95% CI 0·57-0·92]). Prespecified subgroup analyses of the primary outcome supported the primary results. 185 participants reported at least one adverse event; 99 (46%) in the placebo group and 86 (45%) in the brensocatib group. The most common adverse events were gastrointestinal disorders and infections. One death in the placebo group was judged as possibly related to study drug. INTERPRETATION: Brensocatib treatment did not improve clinical status at day 29 in patients hospitalised with COVID-19. FUNDING: Sponsored by the University of Dundee and supported through an Investigator Initiated Research award from Insmed, Bridgewater, NJ; STOP-COVID19 trial.