Anxiety disorders (AD) are common mental disorders, for which several cost-of-illness (COI) studies have been conducted in the past.
The aim of this review was to provide a systematic overview of these studies and an aggregation of their results.
A systematic literature search limited to studies published after 1999 was conducted in PubMed/MEDLINE in November 2018. We included top-down COI studies reporting costs for AD, and bottom-up COI studies reporting costs for AD and a non-diseased control group, and extracted data manually. Results of the top-down COI studies were aggregated by calculating the mean percentage of costs on gross domestic product (GDP) and health expenditure, while the results of the bottom-up studies were analyzed meta-analytically using the ‘ratio of means’ method and inverse-variance pooling. In this review, the logarithm of the relative difference in a continuous outcome between two groups is calculated and aggregated over the studies. The results can be interpreted as the relative change in costs imposed by a specific disease compared with baseline costs.
We identified 13 top-down and 11 bottom-up COI studies. All top-down COI studies and four bottom-up COI studies reported costs for AD as a diagnostic group, four for generalized anxiety disorder (GAD), four for social anxiety disorder (SAD), and one for panic disorder. In top-down COI studies, direct costs of AD, on average, corresponded to 2.08% of health care costs and 0.22% of GDP, whereas indirect costs, on average, corresponded to 0.23% of GDP. In bottom-up COI studies, direct costs of patients with AD were increased by factor 2.17 (1.29–3.67; p = 0.004) and indirect costs were increased by factor 1.92 (1.05–3.53; p = 0.04), whereas total costs increased by factor 2.52 (1.73–3.68; p < 0.001). Subgroup analysis revealed an increase in direct costs by 1.60 (1.16–2.22; p = 0.005) for SAD and 2.60 (2.01–3.36; p < 0.001) for GAD. Measures of heterogeneity indicated high heterogeneity when pooling studies for direct costs, indirect costs, and total costs, but low to moderate heterogeneity when pooling studies for SAD or GAD.
Using methods that focused on relative rather than absolute costs, we were able to aggregate costs reported in different COI studies for ADs. We found that ADs were associated with a low proportion of health care costs on a population level, but significantly increased health care costs on an individual level compared with healthy controls. Our disorder-specific subgroup analysis showed that study findings are most homogeneous within specific ADs. Therefore, to get a more detailed picture of the costs of ADs, more studies for currently under researched ADs, such as panic disorder, are needed.