Drug-disease interactions in Swedish senior primary care patients were dominated by non-steroid anti-inflammatory drugs and hypertension - a population-based registry study.

Drug-disease interactions (DDSIs) are present when a drug prescribed for one disease worsens a concomitant disease. The prevalence of DDSIs in older patients in primary care is largely unknown, as well as to what extent physicians individualize drug prescribing in relation to concomitant diseases. We therefore analysed the prevalence of DDSIs in older patients in primary care and explored to what extent physicians take possible DDSIs into account when prescribing. A total of 336,295 patients aged ≥65 registered with one of the 206 primary care practices in Region Stockholm. Prevalence and prevalence differences for DDSIs. In 10.8% of older patients, at least one DDSI was observed. Non-steroidal anti-inflammatory drugs (NSAIDs) were implicated in more than 75% of cases. The most common DDSI was NSAID/hypertension (8.1%), followed by NSAID/cardiovascular disease and loop diuretics/urinary incontinence (both 0.7%). The use of NSAIDs among patients with heart failure or impaired renal function was 15% lower than among patients without these diseases. DDSIs were present in every tenth older patient in primary care. Patients with cardiovascular disease receive NSAIDs to a lower extent, possibly indicating physician awareness of DDSI. Key points Evidence on the prevalence of drug-disease interactions in older patients in primary care is sparse despite their potential to cause harm. In this study, we found that every 10th older patient attending primary care had at least one drug-disease interaction. Interactions with NSAIDs were far more common than interactions with other drugs. The use of NSAIDs among patients with heart failure or impaired renal function was 15% lower than among patients without these diseases.