Background: U.S. studies using varying methodologies have reported different estimates for the indirect, or nonmedical cost per person with inflammatory bowel disease (IBD). Our analysis contributes to this literature by using the 1999 sample of the National Health Interview Survey (NHIS) to estimate the work-loss effect of IBD on work in the United States and the associated cost to society.
Methods: A weighted logistic regression model was used to estimate the OR of being out of the labor force as determined by predictive variables, including having been diagnosed with IBD, with or without symptoms. Controls included health status indicators and demographic variables. For those people in the labor force, a second analysis was performed to determine the relative influence of the same variables on working less than 12 months versus the entire year. SUDAAN 8.0 was used to generate population estimates, systematically correcting for survey design.
Results: Of IBD patients who had experienced symptoms in the past 12 months, 31.5% reported being out of the labor force (OR = 2.14, relative to the non-IBD group). We estimated the excess in the nonparticipation rate attributable to IBD with symptoms in the past 12 months in the United States to be 12.3%. Based on this, the indirect cost of nonparticipation attributable to IBD in 1998/1999 was more than $3.6 billion U.S. dollars (USD) or $5228 USD per person with IBD and symptoms. According to the second weighted logistic regression, for those who are in the labor force, having IBD had no association with the duration of work.
Conclusions: By using directly observed data in our analysis, this method of estimation can be used to predict the overall paid-employment burden of IBD.