Prevalence, incidence, and determinants of hospital contact due to depression in older adults: A Danish nationwide register-based descriptive study

Abstract

<h3>Introduction</h3> Major depressive disorder (MDD/depression) is one of the most common psychiatric disorders in the rapidly growing aging population, affecting nearly one in every ten older adults (65 years and older). Socio-economic status (SES) is widely described as a risk factor for MDD in older adults while access to care for MDD is also likely to be affected by SES. Equity in access to health care can be defined as equal access for equal needs and can partially be evaluated by assessing the utilization of care services. Denmark is considered an egalitarian county. However, inequality in access to Danish health care has been discussed in the scientific literature. Past studies reported that inequality in access to Danish health care is associated with low SES, old age, ethnicity, living alone, receiving public benefits, and multi-morbidity. Concerning MDD care, studies in different populations have shown that access to MDD care is influenced by gender, age, SES, place of residence, ethnicity, among others. However, existing studies primarily focused on individuals aged below 65 years. We, therefore, describe the pattern of hospital contacts due to MDD in older adults from 2006 to 2018 in Denmark. More specifically, we assess the prevalence and incidence of hospital contacts due to MDD in older adults across various subgroups based on socio-demographic-economic and clinical factors. We further examine whether the pattern of the prevalence and incidence of hospital contact due to MDD in older adults changed over time. Lastly, we explore determinants (associated factors) of hospital contact due to MDD in older adults. <h3>Methods</h3> For studying prevalence, we followed a cross-sectional study design and for the incidence and association study, we carried out a historical cohort study. We used individual data from the Danish nationwide medical and socio-demographic registers linked by a personal identification number. We included all individuals aged 65 and older residing in Denmark in the study period between 2006 to 2018. Individuals who had at least one hospital contact due to MDD (ICD10: F32/F33) during the study period were considered as a case. For incidence and association analyses, we included those individuals who had at least one year of follow-up since they turned age 65. Individuals were censored at the date of death, emigration, hospital contact with MDD, and the end of 2018, whichever came first. Included factors were age, sex, marital status, education, occupation, socio-economic status (based on education and occupation), place of residence (geographical region), country of origin (ethnicity), Charlson comorbidity index within last ten years, somatic and psychiatric hospital contact within the last one year, and calendar year. For association analysis, we applied Poisson regression models and estimated rate ratios (IRR) with their 95% confidence interval (CI). <h3>Results</h3> We identified 28,318 older adults (of 62.6% women) from a total population of 1.54 million aged 65 years or older, who had at least one hospital contact (including in- out and emergency) with a main reason of MDD during 2006-2018. Overall (including sex-stratified), a decreasing trend of both prevalence and incidence was observed during the study period, e.g., the incidence rate was 21 in 2006-2010 and 9 in 2015-2018 per 10,000 PY. Both prevalence and incidence rates were noticeably higher in women than in men. This pattern was consistent throughout all subgroups based on socio-demographical and clinical factors, e.g., in the low SES group, the incidence rate was 15 in men and 23 in women per 10,000 PY. A higher rate of hospital contact due to MDD was associated with older age (age 81-85 vs. age 65-70, IRR, 95% CI: 2.10 (1.91-2.31), being women (vs. men, 1.30, 95% CI: 1.25-135), marital status as being separated (vs. married/registered partner, 1.14, 95% CI: 1.14 (1.06-1.23), living single (vs. couple, 1.24, 95% CI: 1.15-1.33), within last year for each somatic hospital contact (1.05, 95% CI: 1.05-1.06), within last year had a psychiatric hospital contact (vs. had no contact, 1.71, 95% CI: 1.52-1.92), within last ten years for each unit of Charlson index (1.08, 95% CI: 1.06-1.09). Besides, we found that ethnically being non-western, living in the geographical region other than the city of Copenhagen and Funen county, and calendar year as more recent years were significantly associated with a reduced rate of hospital contact due to MDD. <h3>Conclusions</h3> In summary, hospital contacts due to MDD have gradually decreased in past years since 2006 in Danish older adults. Factors associated with the hospital contact due to MDD were e. g., being older, women, single, somatic comorbidity, and previous health care contact. Being of non-western origin had a lower rate of hospital contact due to MDD, but no link between SES and hospital contact was detected. <h3>This research was funded by</h3> The study is funded by The Central Denmark Region's Health Sciences Research Fund