Prediagnostic prescription patterns in pancreatic cancer: a retrospective primary care cohort study.

Abstract

Prescribing patterns in primary care could demonstrate early clinical features of cancer and windows of opportunity for timely investigation. To analyse primary care prescription patterns before a pancreatic cancer diagnosis. Retrospective cohort study using linked primary care and cancer registry data from patients diagnosed with pancreatic cancer in England between 2011 and 2018. Prescription records registered in the Clinical Practice Research Datalink were analysed in the 5 years prediagnosis. Eight categories of prescriptions that may be used to treat clinical features of pancreatic cancer were included (anti-emetics, anti-reflux medications, insulin, other hypoglycaemic agents, opioids, non-opioid analgesics, neuropathic analgesics, and non-steroidal anti-inflammatories). Poisson regression was used to estimate the inflection points for increased prescribing above baseline. Among 12 990 patients, 669 287 prescriptions were analysed. Insulin was the least common prescription (6.9% [<i>n</i> = 892/12 990] of patients), anti-reflux the most common (52.6% [<i>n</i> = 6833/12 990] of patients). Insulin prescribing increased 19 months prediagnosis (95% confidence interval [CI] = 14.2 to 23.8), rising earlier in female patients (25 months; 95% CI = 17.4 to 32.5) than male patients (11 months; 95% CI = 5.8 to 16.2). Prescriptions for other hypoglycaemic agents increased 13 months (95% CI = 7.7 to 18.5), anti-reflux and opioid analgesic prescribing 7 months (95% CI = 5.4 to 8.6 and 4.4 to 9.6, respectively), and anti-emetics and non-opioid analgesics 5 months (95% CI = 2.9 to 7.1 and 3.2 to 6.8, respectively) before diagnosis. The early increase in insulin prescribing suggests tumour-induced type 3c diabetes, highlighting an opportunity for earlier diagnosis in a small proportion of patients. Opportunities for earlier diagnosis through investigation and referral also exist in patients prescribed anti-emetic, anti-reflux, and analgesic medications in primary care.