Work in multiple jobs and the risk of occupational injury in the U.S. working population

Background/Purpose: Up to 20% of workers in the US work more than one job during the year, and approximately 5% report working multiple jobs during the same week. However, occupational injury research has largely explored only exposures at the primary job or the job in which the injury occurred. Also, few publically available surveys collect information on work in multiple jobs and definitions are unclear.

Methods: The National Health Interview Survey, a clustered stratified cross sectional in-household survey, is the only national survey to collect information annually about self-reported injuries in the last 3 months and information about multiple jobs. Using information for years 1998-2010, (overall weighted n = 45,766,948 injuries) we compare characteristics between those who work in one job and those who work in multiple jobs, and also evaluate increased risk to multiple job holders using weighted multiple logistic regression models, controlling for potential confounders (e.g. industry, occupation, race/ethnicity, education).

Results/Outcomes: We expect to find that there are certain characteristic groups of workers who take on multiple jobs which may vary with expansion-recession economic conditions. We also expect to find increased occupational injury risk within certain occupation groups.

Conclusions: Injury risk may increase when working multiple jobs due to factors such as fatigue from the 2nd job, inexperience, and the vacillation between different types of exposure. Therefore injury surveys should collect more information (e.g. type of work and hours worked) about work in multiple jobs because these should be explored regarding the contribution to occupational injury risk.