Combining Statistics from Two National Complex Surveys to Estimate Injury Rates Per Hour Exposed and Variance by Activity in the U.S.

• Activity Number: 375
• Type: Contributed
• Date/Time: Tuesday, August 2, 2016 : 10:30 AM to 12:20 PM
• Sponsor: Section on Statistics in Epidemiology
• Author(s): Tinchi Lin* and Helen Wellman and Joanna Willetts and Santosh Verma
• Companies: Liberty Mutual Research Institute for Safety and Liberty Mutual Research Institute for Safety and Liberty Mutual Research Institute for Safety and Liberty Mutual Research Institute for Safety
• Keywords: injury ; epidemiology ; complex survey ; delta method ; variance estimation

Abstract

A common issue in descriptive injury epidemiology is that to calculate injury rates that account for the time spent in an activity, both injury cases and exposure time need to be collected. In reality, few national surveys have this capacity. To address this issue, we combined statistics from two different national complex surveys as inputs for the numerator and denominator to estimate injury rate. The 2010 National Health Interview Survey (NHIS) was used to quantify injuries, and the 2010 American Time Use Survey (ATUS) was used to quantify time of exposure to specific activities. The variance was calculated using the 'delta method', a general method for variance estimation with complex surveys. Among the five types of injuries examined, 'sport and exercise' had the highest rate (12.64 injuries per 100,000 hours), followed by 'working around house/yard' (6.14). The results show a ranking of injury rate by activity quite different from estimates using population as the denominator. Our approach produces an estimate of injury risk which includes activity exposure time and may more reliably reflect the underlying injury risks.