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

Abstract (English)

BACKGROUND: Prescribing patterns in primary care could demonstrate early clinical features of cancer and windows of opportunity for timely investigation. AIM: To analyse primary care prescription patterns before a pancreatic cancer diagnosis. DESIGN AND SETTING: Retrospective cohort study using linked primary care and cancer registry data from patients diagnosed with pancreatic cancer in England between 2011 and 2018. METHOD: 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. RESULTS: 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. CONCLUSION: 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.