Hourly Trends in Occupational Low Back and Cumulative Trauma Disorders

Abstract

Very few studies have investigated the variations in occupational injuries throughout the day. The main objective of this study was to examine hourly trends in reported claims of occupational injuries with special emphasis on low back disorders (LBDs) and cumulative trauma disorders (CTDs). The data were obtained from the records of a major insurance carrier. The results showed that the number of claims per hour exhibited a Gaussian-like distribution with highest reported numbers occurring between 7:00 am and 11:00 am. There was an observed increase in LBD claims during the morning hours when compared to the afternoon. In addition, there was a pronounced increase in the number of CTD claims at 9 a.m. indicating a possible carry over effect from nocturnal and early morning pain commonly experienced in CTD sufferers. More revealing, normalized claims (per number of people working at a given hour) showed a dramatic increase during the evening and early morning hours when compared to normal working hours. For both the overall and LBD claims, the rates during the night and early morning periods were up to three times higher than during the typical day-time working hours. However, this trend was not as pronounced for the CTD claims. The findings of the study indicate that special attention should be paid to activities and work processes performed during night and early morning hours of the day.