Comorbid Health Conditions and Healthcare Expenditures: A Comparison Study By Mental Illness Status

Background and Purpose: It is critical for mental health professionals to ensure that individuals with serious mental illness also receive appropriate and equitable care for their comorbid health conditions. Individuals with serious mental illness have higher rates of comorbid physical health conditions when compared to the general population. Previous studies also show that the mortality rate of individuals with serious mental illness is two or three times greater than that of the general population. Approximately 60% of this excess mortality for individuals with serious mental illness has been reported to be the result of physical health conditions. The purpose of this study was to compare the extent to which comorbid medical conditions were associated with healthcare expenditures among individuals with serious mental illness, individuals with other mental illness, and individuals without mental illness.

Methods: This study used data obtained from the 2007 Medical Expenditure Panel Survey (MEPS). The nationally representative sample consisted of 13,185 adults (ages 18-64), which included 239 individuals with serious mental illness (ICD-9 codes: 295 or 296), 2,601 individuals with other mental illness, and 10,345 individuals without mental illness. Physical health conditions were identified through ICD-9 codes and then classified into diagnostic groups by using the Elixhauser index. Guided by the Andersen’s behavioral model of health service utilization, a series of OLS regression models were conducted, separately for individuals with serious mental illness, individuals with other mental illness, and individuals without mental illness, to examine the extent to which comorbid health conditions and mental illnesses increase healthcare expenditure. Furthermore, to test whether the magnitudes of the effects of physical health conditions on healthcare expenditures differed by mental illness status, interaction terms between physical and mental illness status were added to the models. To account for the MEPS complex survey design, the survey procedures in SAS were employed in all statistical analyses.

Results: Total healthcare expenditure for individuals with serious mental illness was about 2.9 times greater than that of individuals without mental illness ($10588 vs. $3633, respectively), and 1.6 times greater than that of individuals with mental illness ($10588 vs. $6733, respectively). About 39% of the individuals with serious mental illness had two or more health conditions, while about 59% of the individuals without mental illness had no health condition. With each additional physical health condition, the total healthcare expenditure for individuals with serious mental illness increased by 49.2%, which is approximately $5290. The additional cost burden per medical condition was $4255 for individuals with other mental illness, and $2921 for individuals without mental illness.

Conclusions: Further research considerations are an examination of the degree to which higher healthcare costs may be associated with the timeliness of seeking treatment. Individuals with mental illness may not receive preventive care or early intervention, resulting in more costly care later in their disease process. Also, the quality of the care received may differ as a result of communication problems between provider and patient resulting in higher crisis related costs in the future.