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

Abstract

Abstract Objective 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. Methods 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 3486 individuals with thyroid cancer diagnosed during 2005-2019. Prevalence ratios (PRs) with 95% CIs 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. Results Individuals (both males and females) with thyroid cancer had higher use of drugs for several chronic conditions in the years after diagnosis; eg, 5 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 with the cancer-free population. In addition, males with thyroid cancer had long-term elevated use of drugs for depression (eg, 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, eg, hypertension, gastric acid disorders, and pain. Conclusions Individuals diagnosed with thyroid cancer had elevated long-term use of drugs for several chronic conditions, as compared with the cancer-free population.