Risk of myocardial infarction associated with non-steroidal anti-inflammatory drugs: Impact of additional confounding control for variables collected from self-reported data

What is known and objective Important risk factors and over-the-counter (OTC) dispensing of non-steroidal anti-inflammatory drugs (NSAIDs) are often not routinely recorded in electronic health records. This study aimed to assess the impact of patient's reports on these factors on the risk of acute myocardial infarction (AMI) for NSAID use. Methods A nested case-control study was conducted among adults in the Utrecht Cardiovascular Pharmacogenetics study. Cases were patients with a first diagnosis of AMI as a hospital discharge diagnosis and controls were those without AMI. NSAID exposure was either current use of selective COX-2 inhibitors or conventional NSAIDs. Information was collected from The Dutch PHARMO Database Network (pharmacy records of drug dispensing linked to hospitalization records) and the patient's questionnaire (lifestyle factors, body mass index and history of cardiovascular diseases). Unconditional logistic regression analysis was used to calculate odds ratios (ORs) and to control for confounding factors. Results We identified 970 AMI cases and 2974 controls. Among cases, 11 (1.1%) and 185 (19.1%) were exposed to selective COX-2 inhibitors and conventional NSAIDs, respectively. Compared to non-use, none of these drug classes were associated with an increased risk of AMI (adjusted OR 1.07, 95% CI: 0.52-2.18 and 0.93, 95% CI: 0.77-1.12, respectively). Additional adjustment for potential confounders from patient's reports did not change the risk estimates (adjusted OR 1.08, 95% CI: 0.53-2.22 and 0.89, 95% CI: 0.73-1.09, respectively). What is new and conclusion Additional confounding control for variables from self-reported data or considering self-reported OTC NSAID use did not change the risk estimates for the association between NSAIDs and AMI.