Association between Mental Disorders and Subsequent Medical Conditions

Abstract

Background: Persons with mental disorders are at a higher risk than the general population for the subsequent development of certain medical conditions.

Methods: We used a population-based cohort from Danish national registries that included data on more than 5.9 million persons born in Denmark from 1900 through 2015 and followed them from 2000 through 2016, for a total of 83.9 million person-years. We assessed 10 broad types of mental disorders and 9 broad categories of medical conditions (which encompassed 31 specific conditions). We used Cox regression models to calculate overall hazard ratios and time-dependent hazard ratios for pairs of mental disorders and medical conditions, after adjustment for age, sex, calendar time, and previous mental disorders. Absolute risks were estimated with the use of competing-risks survival analyses.

Results: A total of 698,874 of 5,940,299 persons (11.8%) were identified as having a mental disorder. The median age of the total population was 32.1 years at entry into the cohort and 48.7 years at the time of the last follow-up. Persons with a mental disorder had a higher risk than those without such disorders with respect to 76 of 90 pairs of mental disorders and medical conditions. The median hazard ratio for an association between a mental disorder and a medical condition was 1.37. The lowest hazard ratio was 0.82 for organic mental disorders and the broad category of cancer (95% confidence interval [CI], 0.80 to 0.84), and the highest was 3.62 for eating disorders and urogenital conditions (95% CI, 3.11 to 4.22). Several specific pairs showed a reduced risk (e.g., schizophrenia and musculoskeletal conditions). Risks varied according to the time since the diagnosis of a mental disorder. The absolute risk of a medical condition within 15 years after a mental disorder was diagnosed varied from 0.6% for a urogenital condition among persons with a developmental disorder to 54.1% for a circulatory disorder among those with an organic mental disorder.

Conclusions: Most mental disorders were associated with an increased risk of a subsequent medical condition; hazard ratios ranged from 0.82 to 3.62 and varied according to the time since the diagnosis of the mental disorder. (Funded by the Danish National Research Foundation and others; COMO-GMC ClinicalTrials.gov number, NCT03847753.).

Figure 1.. Risk of a Medical Condition after the Diagnosis of a Mental Disorder, According to Category.

Each panel shows the pairwise risk of a medical condition (listed at the left of the graphs) after the diagnosis of a mental disorder (indicated at the top of each panel). Estimates were calculated with the use of Cox proportional-hazards models with age as the underlying time scale, after adjustment for sex and calendar time (model A) and after further adjustment for other mental disorders that had an onset before the mental disorder under study (model B). The line of unity is shown as a dashed line in each plot. Hazard ratios are shown on a log scale. I bars indicate confidence intervals.

Figure 2.. Risk of a Medical Condition after the Diagnosis of a Mood Disorder, According to the Timing of the Diagnosis.

Each panel shows the time-dependent hazard ratios for a medical condition after the diagnosis of a mood disorder, according to two models. Estimates were obtained with the use of Cox proportional-hazards models with age as the underlying time scale, after adjustment for sex and calendar time (model A) and after further adjustment for other mental disorders that had an onset before the mental disorder under study (model B). The line of unity is shown as a dashed line in each plot. The horizontal axes show the time period since the first diagnosis of a mood disorder. All other pairwise comparisons between mental disorders and medical conditions are shown in Figures S23 through S62.

Figure 3.. Risk of a Medical Condition after the Diagnosis of a Mood Disorder, According to Sex and the Time since the Diagnosis.

Shown is the risk (as measured by cumulative incidence per 100 persons) of a medical condition after the diagnosis of a mood disorder, according to sex and the category of medical condition. Panel A shows the estimates among all the persons in the study, according to the time since the diagnosis of the mood disorder. Panel B shows the risk of a circulatory condition according to the age at the time of the diagnosis of a mood disorder, with the time since the diagnosis of the mood disorder shown on the horizontal axes. The 95% confidence intervals (indicated by shaded gray areas around the curves) are so small that they are obscured by the estimate curves in Panel A and are visible only in the graph at the far right in Panel B. The absolute risks of all other pairs of mental disorders and medical conditions are shown in Figures S63 through S142.