1. The Impact of Hidradenitis Suppurativa on Work Loss, Indirect Costs, and Income
T. Tzellos1,2; H. Yang3; F. Mu3; B. Calimlim4; J. Signorovitch3
1 Department of Dermatology, Faculty of Health Sciences, University Hospital of North Norway, Troms, Norway
2 Department of Clinical Medicine, Arctic University, Tromsø, Norway
3 Analysis Group, Inc., 111 Huntington Ave, Floor 14, Boston, MA USA
4 AbbVie, Inc., 1 N. Waukegan Road, North Chicago, IL USA
British Journal of Dermatology. DOI: /bjd.17101

2. Lead researcher
Thrasyvoulos Tzellos, MSc, Ph.D.

3. Introduction What’s already known?
Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease which could interfere with patients’ daily life and ability to work

4. Objective
This retrospective cohort study evaluated the indirect burden among patients with HS in the US, including:
Income
Risk of leaving the workforce
Days of work loss
Indirect costs

5. Methods Data source Study population and study cohorts
Private insurance database (OptumHealth Care Solutions, Inc.,1999 Q1 to 2015 Q1)
Study population and study cohorts
Newly diagnosed HS cohort: to evaluate the impact of HS on income and risk of leaving the workforce
General HS cohort: randomly selected patients with HS, for evaluating the impact of HS on annual income, work loss days, and annual indirect costs
Inclusion criteria: ≥2 diagnoses for HS, continuous enrollment in a healthcare plan, aged years, employed, income data available
The general HS cohort were required to have work loss data
Controls: patients without any HS diagnosis, matched 5:1 to HS cohorts on sex, birth year, index year and region

6. Methods (Continued) Study measures Baseline characteristics
Demographics
Comorbidities
Annual income (2015 USD)
Total work loss days (general HS/control cohorts)
Annual indirect costs (general HS/control cohorts; 2015 USD)

7. Methods (Continued) Study outcomes
Among the newly diagnosed HS/control cohorts (5 years of follow up)
Income growth over time (2015 USD)
Risk of leaving the workforce
Among the general HS/control cohorts (1 year of follow up)
Days of work loss
Annual indirect costs (2015 USD)
Annual income (2015 USD)

8. Methods (Continued) Statistical methods Income growth over time:
Multivariable generalized linear mixed model adjusting for the modified Charlson comorbidity index (CCI) and baseline annual income
Risk of leaving the workforce:
Kaplan-Meier analyses, log-rank tests, and Cox proportional hazards models adjusting for the modified CCI
Incidence rates of work loss days per patient year, annual indirect costs, and annual income:
Described and compared between study cohorts using multivariable generalized estimating equations models adjusting for modified CCI and health insurance plan

9. Results
1,003 newly diagnosed HS patients were matched with 5,015 controls for the analysis of income growth
After the first year, income growth for the HS cohort was on average $324 less per year than for the control cohort (p=0.002)

10. Results (Continued)
798 newly diagnosed HS patients and 3,990 matched controls had work loss data available and were included in the risk of leaving the workforce analysis
Over the 5 years following HS diagnosis, patients with HS were more likely to experience a work leave event, including a leave of absence, short-term disability, and long-term disability
Adjusted HR (95% CI)
HS vs. control
P-Value
Any event
1.65 (1.45, 1.88)
<0.001 *
Leave of absence
1.64 (1.40, 1.93)
Short-term disability
1.94 (1.67, 2.24)
Long-term disability
2.12 (1.02, 4.42)
0.044
Early retirement
0.40 (0.23, 0.70)
0.001
*p<0.05; CI: confidence interval; HR: hazard ratio

11. Results (Continued)
The general HS cohort was composed of 1,204 patients with HS who were matched with 6,020 controls for the work loss and indirect costs analyses
Patients with HS had significantly more total days of work loss and significantly higher total annual indirect costs compared with controls
*p<0.05; CI: confidence interval; IRR: incidence rate ratio; USD: US dollar

12. Discussion
To date, there is limited information on the indirect burden of HS in the published literature
To the best of our knowledge, this is the first study to assess the indirect burden of HS on income growth, indirect costs, and the risk of leaving the workforce among privately insured patients with HS in the US

13. Discussion (Continued)
The current approach has several strengths:
Various components of the indirect burden associated with HS were assessed in this study
The indirect burden of HS was assessed from the perspectives of both newly diagnosed and general (incident/prevalent) patients with HS
Matching between HS and the controls, and multivariable regression analyses helped separate the impact of HS from other confounding factors

14. Discussion (Continued)
The results of this study should be considered in light of several limitations:
We could not consider disease severity because the database did not contain this information
The reasons for leaving the workforce were not available and therefore HS-specific events leading to leaving the workforce could not be evaluated
Lastly, as the cost of presentisms was not captured in this study, the indirect costs may have been underestimated

15. Conclusions What does this study add?
This retrospective claims analysis found that HS is associated with high indirect burden (i.e., slower income growth, higher risk of leaving the workforce, and higher indirect costs)
These results indicate that HS patients have unmet disease management needs

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