Effects of screening for anxiety and depression in patients with ischaemic heart disease - a nationwide Danish register study.

Abstract

To investigate the effect of screening for anxiety and depression (AD) in patients with ischaemic heart disease (IHD) on the likelihood of receiving treatment for AD. We used a nationwide dataset of all Danish patients with an incident IHD diagnosis in the period 2015-2018 (N = 80,701) of which 20,461 (25%) were exposed to screening for AD as part of cardiac rehabilitation. A binary composite indicator for the use of any AD treatment (prescriptions of AD drugs, general practitioner (GP) counselling or referral to a psychologist), was modelled as the dependent variable. The probability of receiving AD treatment was estimated using linear probability and instrumental variable regression models. Exposure to AD screening was lower for patients with low income (change in probability -0.67, 95% CI -0.76; -0.59), low education (change in probability -0.16, 95% CI -0.20; -0.13), and a high comorbidity burden (change in probability -0.09, 95% CI -0.10; -0.07). Screened patients had a lower conditional probability of AD treatment (change in probability -0.0061, p < 0.001) than non-screened patients. The patient's GP also had an impact on the probability of being referred for AD treatment. Using an instrumental variable approach did not affect the results. Screening for AD was subject to selection at the patient level; patients at lower risk of AD had a higher probability of being screened. Hence, extending systematic screening to cover a larger population may not achieve a noticeable increase in the uptake of AD treatment if it is not supported by appropriate measures to reduce reverse selection into screening.