Mental distress severity among Florida adults: A comparison of outcomes using two measures

Background: Frequent mental distress (FMD) is a dichotomous variable constructed using a single core question (CQ) from the Behavioral Risk Factor Surveillance System (BRFSS) instrument and uses a cut-point of 14 out of 30 days with poor mental health. The BRFSS has an optional "Anxiety and Depression" module (ADM) that uses 8 questions about mental distress (MD) and has been used to construct a five-level MD index of severity (ADMDI).  Using FMD negates the ability to examine MD and related outcomes across a spectrum of severity. The purpose of this study is to describe the methods used for construction of a five-level MD severity index variable using responses from the single BRFSS core MD question (CQMDI) and describe the patterns of chronic disease-related outcomes by mental distress severity among Florida adults. Methods: Using data from the national 2006 BRFSS AD Module (n=170,814), the ADMDI variable was constructed in a manner consistent with the methods described in the peer-reviewed literature. The CQMDI was constructed by finding AD-analogous cut points from the CQ used to construct FMD.  The CQMDI variable was tested for reliability against the ADMDI variable and the eight questions in the AD module and found to have acceptable reliability in each comparison (Cronbach alpha values >=0.70). A descriptive analysis of FMD and CQMDI was conducted using 2010 Florida BRFSS data. Results: Using FMD, 88.2% of Florida adults have no FMD. Using the CQMDI, 79.7% of Florida adults do not have significant mental distress (CQMDI=1) and 7.2% of adults have severe mental distress (CQMDI=5). A significant proportion of adults with no FMD have some degree of mental distress and that over 60% of those with FMD have severe mental distress. Logistic regression interpretations for a number of commonly examined dependent variables varied depending on whether FMD or CQMDI is included as an independent variable. Conclusion: The CQMDI variable has acceptable reliability compared to the ADMDI variable. Using the CQMDI variable enables more frequent and more detailed examinations of health outcomes related to MD using national and state-specific BRFSS data.