In this study, we evaluated the effect of CI on mental healthcare costs in a sample of 62 older, ethnically diverse, low-income participants. Our sample was largely comprised individuals with mood disorders and psychotic disorders, and 61% of the sample demonstrated CI consistent with our previous study evaluating CI in individuals with severe psychiatric illness.37
Our results indicate that cognitively impaired individuals had mental healthcare costs than were nearly double that of cognitively intact individuals over each of the intervals assessed. Furthermore, when controlling for other demographic and clinical variables, both ethnicity and CI were significant predictors of mental healthcare costs in this sample.
Our finding that CI was significantly associated with mental healthcare costs was expected given numerous studies suggesting the potential for CI to directly affect mental healthcare costs through associations with poor mental health outcomes, treatment nonadherence, poor medical decision making ability, and high rates of emergency room services utilization.18–31,34,57
Additionally, CI may serve as a phenotypic marker of individuals with greater medical burden and/or neurodegenerative disease,58–65
which could also strengthen the association between CI and mental healthcare costs given commonly documented relationships between medical burden and psychiatric treatment outcomes.66
Nonetheless, to our knowledge, this is the first study to investigate the relationship of clinically defined CI to mental healthcare costs specifically for older, low-income adults with severe psychiatric illness, and our results suggest that CI is a significant factor in mental healthcare costs in this population.
In comparison with another recent study evaluating the effect of cognitive functioning on 6-month healthcare costs among younger schizophrenic patients,46
our sample had significantly lower mental healthcare costs during a 6-month interval ($8,145 versus $23,824). Although direct comparisons of cost of mental healthcare costs between these two studies is difficult due to different methodology used and different clinical characteristics of the sample, it seems that the discrepancies in costs between the two samples studies can largely be accounted for by inclusion of the cost of specialized/inpatient accommodations ($14,882) and medication costs ($1,407) that were included in the study by Patel et al., which were not included in our analyses. After removing these costs, the 6-month mental healthcare costs for our sample of older adults would be slightly higher than costs for the younger sample. Similarly, when referenced to the costs of medical treatment for individuals with psychiatric symptoms in adults in a Medicaid health maintenance organization sample during a 12-month interval ($6,995),11
the 12-month mental healthcare costs for individuals with severe psychiatric illness in our sample was significantly higher ($20,615). We would suggest that that these differences are largely due to the fact participants in our sample likely had more severe and chronic psychiatric illness, in addition to a higher incidence of CI, than the Medicaid sample. Taken collectively, these comparisons further support our conclusions that CI in older adults with severe psychiatric illness is a significant contributor to increased mental healthcare costs.
Our finding that ethnicity was a significant predictor of mental healthcare costs is also not surprising given consistent literature suggesting under utilization of mental health treatment among ethnic minority groups,67,68
which may have contributed to the association between cost of service and ethnicity. However, although our sample comprised ethnically diverse individuals, our sample size did not allow us to adequately evaluate the effect of specific ethnic groups on mental healthcare costs, which is a limitation of the study. Because of this limitation, we are not able to determine whether specific ethnic minority groups in our sample had lower mental healthcare costs relative to other minority groups; but overall, our findings that white participants did not differ significantly on mental healthcare costs from nonwhite participants on group comparisons suggests that the effect of ethnicity on mental healthcare costs was relatively weak in relationship to the effect of CI on these costs.
Our study is not without other limitations, and it is important to discuss these in relationship to our findings. In our view, the most significant limitation of this study is that we evaluated mental healthcare costs for time intervals preceding the neuropsychological assessment. Although we suspect that the CIs demonstrated in this sample are largely due to the sequelae of chronic psychiatric illness, and, therefore, presumed to be relatively stable over time, our study design did not allow us to determine whether CI was present during the entire 24-month period for which mental healthcare costs were calculated. Similarly, for individuals who were not diagnosed with CI, we cannot rule out the possibility that these individuals may have experienced cognitive deficits secondary to psychiatric illness that resolved following successful treatment of psychiatric symptoms at some point during this 2-year interval. Therefore, we believe that our results should be interpreted cautiously and that further study on both the chronicity of CI in this patient population and the degree to which a diagnosis of CI predicts future mental healthcare costs is necessary.
As stated previously, another limitation of our study is the relatively small sample size utilized. Our sample size may have obscured potential differences in mental healthcare costs between individuals with a primary diagnosis of mood disorder, when compared with psychotic disorders and also may have contributed a lack of statistical significance of other clinical and demographic predictors of mental healthcare costs. A further limitation of the study includes our use of psychiatric diagnoses obtained from a medical chart review and while such an approach is routinely utilized to evaluate the effect of psychiatric diagnosis on mental healthcare costs, because we did not conduct detailed psychiatric interviews for participants, we acknowledge that participants may have been misdiagnosed. Similarly, we included five individuals in our study that did not have a documented mental health diagnosis specified in their medical record. We included these individuals in our group comparisons because although a mental health diagnosis was not documented in their medical record, these individuals were receiving treatment at the mental health center and as such were representative of the patient population in these treatment centers. We also did not have access to costs of the medications used to treat psychiatric conditions, which we believe would be an important aspect of these mental healthcare costs given findings that medication costs are a significant factor in these costs in other samples.46
Similarly, our study design did not include obtaining information about treatment adherence, concurrent medical conditions, or degree of social support to determine the effect of these factors on mental healthcare costs. An additional limitation of this study was that the cognitive assessment conducted was not comprehensive, and we did not obtain a detailed medical history or obtain an informant history of a decline in the patients’ functional ability, which would be required for a formal diagnosis of dementia or mild CI. Finally, we also acknowledge that our investigation is also limited by a potential participant selection bias in that individuals with cognitive difficulties may have been less likely to volunteer to participate in this investigation.
Despite the limitations of this study, we believe that our results provide compelling evidence that CI is significant factor contributing to mental healthcare costs for individuals with severe psychiatric illness receiving treatment at community mental health centers. Future study will be necessary to determine the specific mechanisms contributing to these increased costs and the degree to which targeted interventions for individuals with CI may reduce mental healthcare costs in these treatment settings. Previous studies have demonstrated that cognitively impaired individuals can benefit from mental health interventions but often need more intensive approaches to treatment.28
Therefore, although targeted interventions may be more costly during shorter time intervals because of more intensive treatment, these interventions may reduce long-term mental healthcare costs by improving outcomes. This potential to reduce mental healthcare costs by developing tailored interventions for individuals with CI is particularly relevant for community mental health centers given the high prevalence of CI in this patient population and the high cost of mental health-care in these settings.