Ammad Mahmood, MBChB

Dalli LL, Kim J, Cadilhac DA, Greenland M, Sanfilippo FM, Andrew NE, Thrift AG, Grimley R, Lindley RI, Sundararajan V, et al. Greater Adherence to Secondary Prevention Medications Improves Survival After Stroke or Transient Ischemic Attack: A Linked Registry Study. Stroke. 2021.

Previous studies of medication adherence poststroke have used an arbitrary cut off of 80% adherence as signifying good adherence, with even 30-40% adherence considered to be “intermediate.” In this retrospective registry study, clinical data from the Australian Stroke Clinical Registry was linked with nationwide prescription refill and mortality data. Rather than focus on a cut-off, the authors utilized “restricted cubic spline” Cox regression to study the effect of a spectrum of adherence on outcome. They focused on adherence to antihypertensives, statins and non-aspirin antithrombotic agents amongst patients during the first year after first ever stroke or TIA and its link with all-cause mortality up to 3 years post-hospital discharge.

A total of 8363 stroke survivors were studied, 44% aged >75 and 44% female. Seventy-five percent were prescribed antihypertensives, and amongst those without ICH, 84% were prescribed statins and 65% prescribed non-aspirin antithrombotics. Median adherence was ~90% in each medication group. Interestingly, their data suggest that >60% adherence, each 10% increase in adherence was associated with a reduction in all-cause mortality as follows:

  • 13% for antihypertensive agents (hazard ratio, 0.87 [95% CI, 0.81–0.95])
  • 13% for statins (hazard ratio, 0.87 [95% CI, 0.80–0.95])
  • 15% for non-aspirin antithrombotic agents (hazard ratio, 0.85 [95% CI, 0.79–0.93]).

The authors acknowledged several limitations of the study, primarily that data examined prescription refills and not whether the collected medication was taken by each individual. Those with good adherence may also be likely to engage in other behaviors which can improve overall health, such as smoking cessation or improved diet and exercise.

Whilst unable to shed light on some of the many medical, social, cultural or financial reasons for reduced adherence with medication, the data presented here are of interest. The possible incrementing benefits of increased adherence even in those with existing “good” adherence highlight the need to explore reasons for non-adherence and how these are best addressed.