Prevalence of drugs used for chronic conditions after diagnosis of thyroid cancer: A register-based cohort study.

Abstract

Little is known about thyroid cancer survivors' risk of chronic conditions. We therefore investigated the prevalence of drugs used for chronic conditions among thyroid cancer patients using population-wide register data. We linked data from the Cancer Registry of Norway to the Norwegian Prescription Database and other databases for a study population of 3.52 million individuals, including 3,486 individuals with thyroid cancer diagnosed during 2005-2019. Prevalence ratios (PR) with 95% confidence intervals (95%CI) of reimbursed prescribed drugs in thyroid cancer patients up to 15 years after thyroid cancer diagnosis, were estimated by log-binomial regression, with the cancer-free population as reference. Individuals (both males and females) with thyroid cancer had higher use of drugs for several chronic conditions in the years after diagnosis. E.g., five years after thyroid cancer diagnosis there was elevated use of drugs for hypoparathyroidism (PRmales=35.4, 95%CI 25.2-49.7; PRfemales=42.8, 95%CI 34.2-53.6), hypertension (PRfemales=1.20, 95%CI 1.12-1.28), anxiety and tension (PRmales=4.01 95%CI 1.80-8.92); PRfemales=2.01, 95%CI 1.15-3.52), gastric acid disorders (PRmales=1.52, 95%CI 1.22-1.91; PRfemales=1.45, 95%CI 1.27-1.66) and pain (PRmales=1.48, 95%CI 1.11-1.97; PRfemales=1.24, 95%CI 1.08-1.42) as compared to the cancer-free population. In addition, males with thyroid cancer had long-term elevated use of drugs for depression (e.g., year 10+, PRmales=1.66, 95%CI 1.06-2.59). Individuals with thyroid cancer also had higher use of drugs for several conditions prior to the thyroid cancer diagnosis, e.g., hypertension, gastric acid disorders and pain. Individuals diagnosed with thyroid cancer had elevated long-term use of drugs for several chronic conditions, as compared to the cancer-free population.