Acceptable medication non-adherence: A crowdsourcing study among French physicians for commonly prescribed medications

Abstract

Background: Achieving good medication adherence is a major challenge for patients with chronic conditions. Our study aimed to assess the Threshold for Unacceptable Risk of Non-adherence (TURN), defined as the threshold at which physicians consider the health risks incurred by patients due to medication non-adherence unacceptable, for the most commonly prescribed drugs in France.

Methods: We conducted an online study using a crowdsourcing approach among French general practitioners and specialists from September 2016 to August 2017. Physicians assessed the TURN for various levels of missed doses by evaluating a series of randomly presented clinical vignettes, each presenting a given medication with a given therapeutic indication. For each "drug-indication group" (i.e., all drugs from the same pharmacological class with a similar therapeutic indication): 1) we described the distribution of physicians' assessments, 2) we provided a summary estimate of the TURN, defined as the frequency of missed doses above which 75% of the physicians' assessments were located; 3) we computed the number of pill boxes reimbursed in France in 2016 to put our results into context.

Results: We collected a total of 5365 assessments from 544 physicians, each of whom evaluated a random sample among 528 distinct clinical vignettes. Estimates of the TURN varied widely across drug-indication groups, ranging from risk considered unacceptable with 1 daily dose missed per month (e.g., insulin for diabetes) to risk always considered acceptable (e.g., anti-dementia drugs). Drugs with an estimated TURN of over one missing daily dose per week represented 44.9% of the prescription volume of the medications assessed in our study.

Conclusions: According to physicians, the impact of non-adherence may vary greatly. Patient-physician discussions on the variable consequences of non-adherence could lead to a paradigm shift by seeking to reach "optimal adherence" depending on drugs rather than unrealistic "perfect adherence" to all drugs.

Fig 1. Distribution of physicians’ estimates: Threshold for Unacceptable Risk of Non-Adherence for 70 drug-indication groups.

Each horizontal bar represents the distribution (in percentage) of physicians’ estimates for a given drug-indication group. TURN* corresponds to the frequency of missing doses above which 75% of physicians’ estimates were located (vertical dashed line). n* corresponds to the number of physicians’ assessments for each drug-indication group. For sake of clarity, we plotted 70 drug-indication groups corresponding to 90% of total prescription volume of the medications assessed in the study. All the 112 drug-indication groups are plotted in S2 Fig. Abbreviations: ACE: angiotensin-converting enzyme, ARBs: angiotensin receptor blockers, CCBs: calcium channel blockers; COPD: Chronic Obstructive Pulmonary Disease; GORD: gastro-oesophageal reflux diseases; HBP: high blood pressure; NSAIDs: non-steroidal anti-inflammatory drugs, MI: myocardial infarction.

Fig 2. Threshold for Unacceptable Risk of Non-Adherence (TURN) and prescription volume for 112 drug-indication groups.

TURN* corresponds to the frequency of missing doses above which 75% of physicians’ estimates were located for each drug-indication group. Results with alternative cut-offs are detailed in S2 Table. Each drug-indication group is plotted as a rectangle: 1) rectangle color corresponds to the TURN*; 2) rectangle area size is proportional to the number of pill boxes reimbursed in 2016 in France (according to the French national health insurance database). We summed the number of pill boxes for the medications belonging to each group. In case of several therapeutic indications for a same medication, we divided the number of pill boxes by the number of indications. Abbreviations: ACE: angiotensin-converting enzyme, ARBs: angiotensin receptor blockers, CCBs: calcium channel blockers; COPD: Chronic Obstructive Pulmonary Disease; GORD: gastro-oesophageal reflux diseases; HBP: high blood pressure; NSAIDs: non-steroidal anti-inflammatory drugs, MI: myocardial infarction.