OBJECTIVES : This research aimed to explore the impact of comorbidities on healthcare expenditures among adults with psoriasis compared to propensity score matched non-psoriasis controls in the United States (US).

METHODS : This study utilized a retrospective, cross-sectional, matched case-control study design by pooling Medical Expenditure Panel Survey (MEPS) data (2010-2015). The eligible study sample comprised of adults (age ≥ 18 years), who were alive during the calendar year and reported positive healthcare expenditure. Individuals with psoriasis (case group) were identified using the ICD-9-CM code of 696 and did not report any joint pain during the 12 months preceding the survey, whereas the control group consisted of adults who did not have any psoriasis diagnosis. The case and control groups were matched on propensity scores generated based on socioeconomic and clinical factors. A series of Ordinary Least Square (OLS) regressions on log-transformed expenditures were conducted to examine the influence of comorbidities on healthcare expenditures (total, emergency room, inpatient, prescription, outpatient, home healthcare and other) among adults with psoriasis. Semi-logarithmic equation (e^β – 1) was used to calculate the percent difference in costs between cases and controls.

RESULTS : Adults with psoriasis had significantly higher yearly average total healthcare expenditures ($8,753 vs. $5429, p<0.001), outpatient expenditures ($3810 vs $1983, p<0.001), and prescription expenditures ($3312 vs $2017, p<0.001) compared to matched controls. Comorbid conditions such as diabetes and eye disorders among adults with psoriasis were associated with significantly higher yearly average total expenditures ($16956 vs $4106, p<0.05; $35295 vs $6661, p<0.05 respectively) compared to matched controls. OLS regressions suggest that total, outpatient and prescription cost differences between adults with psoriasis and matched controls reduced modestly by 13%, 9% and 10% respectively due to comorbidities.

CONCLUSIONS : These findings suggest that in this US nationally representative sample of adults with psoriasis, comorbidities modestly impact excess healthcare expenditures.