OBJECTIVES: To assess real-world trends and drivers of costs and comorbidities using a multiple cohort design in a case study of severe obesity.

METHODS: National Inpatient Sample (NIS) records for 2016 were searched for severe obesity due to excess calories. Five cohorts were designed: (1) all hospitalizations, (2) above the 90th percentile by charges, (3) below the 90th percentile by charges, (4) above the 90th percentile by comorbidity score, (5) below the 90th percentile by comorbidity score. The comorbidity rates were assessed using three methods: Charlson index, Elixhauser and broad ICD-10 categories. The top codes and categories of codes for primary diagnoses were compared across all cohorts.

RESULTS: In 2016, there were an estimated 1,884,275 hospitalizations in the United States with a diagnosis of severe obesity due to excess calories. The mean hospital length of stay (LOS) in 5 cohorts-all, above and below the 90th percentile for charges and comorbid score were: 4.97 (SD 6.18), 11.42 (SD 13.25), 4.06 (SD 3.48), 8.59 (SD 9.19) and 4.77 (SD 5.9) days, respectively. The total charges were $56643 (SD 83559), $220,997 (SD 184653), $38,382 (SD 25195.94), $90,944 (SD 128081.81), $54,748 (SD 79955), respectively. The mortality rate in the five cohorts was 1.53%, 4.92%, 1.05%, 6.34%, and 1.26%, respectively. The highest LOS, charges and mortality were in the 90 percentile by charges and comorbid score. The comorbidity rates also show similar trends, for example for congestive heart failure, the rates in 5 cohorts were 26%, 33%, 25%, 83% and 23%. The principal diagnosis code was Sepsis for two cohorts: the 90th percentile by charges and comorbidity score (versus severe obesity for the other three cohorts).

CONCLUSIONS: Analyses of real-world evidence by top percentiles in terms of charges and comorbidity scores may help providers and payers develop more efficient patient management systems.