Implementation of health care data for identifying, measuring, and mapping chronic comorbidities in Mississippi, 2010-2012

Background: In addition to increasing morbidity and mortality, coexisting morbid conditions impact health care delivery, leading to frequent readmissions and increased health care costs. Mississippi hospital discharge data contain one primary and ten secondary diagnoses, presenting a cost-effective and evidence-based way to study both index diseases and comorbid conditions. The goal of this study was to establish comorbidity levels and patterns, measure resource utilization, and determine demographic and geographical variations in the comorbidity burden among Mississippi’s hospitalized patients.

Methods: The Charlson/Deyo Comorbidity Index, a risk adjustment algorithm based on seventeen major chronic conditions, was implemented to compute the weighted scores and numbers of coexisting morbidities. Mean scores were compared with t-test for continuous variables and proportions with Chi-square test for categorical variables. Mississippi hospital discharge data for 2010-2012 were analyzed with SAS 9.3 and the study included only Mississippi residents.

Results: Among the 1,074,697 patients discharged, 45.2% had a comorbidity score ≥ 1. Further analysis of the weighted comorbidity scores revealed that 25.2% of all patients discharged had a comorbidity score ≥ 2 and 13.4% had a comorbidity score ≥ 3. Diabetes was the leading comorbidity and a concomitant diagnosis in nearly one fifth (17.8%) of all hospitalizations. Chronic pulmonary disease (12.9%), congestive heart failure (11.0%), and renal diseases (9.0%) were the second, third, and fourth leading comorbidities. The mean age on admission was 37.9 years for patients with a comorbidity score of zero and 65.0 years for patients with a comorbidity score of one or higher.  Males were more likely than females (49.6% versus 42.1%, p < 0.001) and Caucasians were more likely than African Americans (45.9% versus 44.7%, p < 0.001) to have a comorbidity score ≥ 1. The mean length of stay (4.8 days versus 6.3 days, p < 0.001) and total charges ($20, 966 versus $33,848, p < 0.001) were higher for discharges associated with a comorbidity score ≥ 1. Hospitalizations of patients residing in rural areas were more likely to have at least one comorbid diagnosis than hospitalizations of patients residing in metro areas (46.4% versus 43.2%, p < 0.001).

Conclusion: This study demonstrated that nearly half of all Mississippi hospitalizations were associated with at least one comorbid diagnosis. Furthermore, diabetes was a major comorbidity in the hospitalized population and rural patients had higher comorbidity levels. These findings could help design new state initiatives that support the effective management of complex medical conditions.