Risk factors for injuries in small and medium sized construction companies
2012-06
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Risk factors for injuries in small and medium sized construction companies
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2012-06
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Abstract
Background
Construction work is hazardous and often physically demanding and strenuous. The industry has a high rate of fatal injuries and contributes a high number of severe and non-fatal injuries. Small construction firms dominate the industry but published data pertaining to health and safety are limited. Those employed in the construction industry consistently rank in the top of all occupations and industries for illicit drug and heavy alcohol use. Additionally, hazards in the industry may be modified by human and organizational elements, as well as contact with a safety and health professional. In this study we examined risk factors for injury and increased injury severity in small-and-medium sized construction companies.
Methods
Workers’ compensation claims data were evaluated covering 1,360 construction companies from 2004-2009. Four different hypotheses were tested.
For the first hypothesis our goal was to determine the associations between active company drug testing programs, injury rate, and severity; presence of a testing program was obtained from the compensation carrier. Hours at-risk and injury claims were used to determine injury rates. Drug testing programs were classified into two categories: pre-employment and post-accident, or pre-employment, post-accident, random, and suspicion testing. Rate ratios (RR) and 95% confidence intervals (CI) were estimated as a function of injury rate using a Poisson regression model and accounting for time-dependent factors. Generalized estimating equations were used to account for correlated observations within companies over time. Models include confounding covariates of company size, union status, and trade.
For the second hypothesis our goal was to determine the association of safety professionals’ evaluations of management attitude and commitment to safety on injury rate and severity. Employee hours at-risk and claims were used to determine injury rates Rating of management attitude was done by safety professionals, employed by the insurance carrier, upon initial visit to member companies. A company had no rating until the initial visit. Based on an evaluation process to characterize hazard control practices of a company, and interactions between the company and safety professional, an attitude and commitment rating was assigned. Rate ratios (RR) and 95% confidence intervals (CI) were estimated as a function of injury rate using a Poisson regression model. Generalized estimating equations were used to account for correlated observations within companies. Models included confounding covariates of company size, union status, and trade.
For the third hypothesis, our goal was to determine the association of medical claims on risk of incidence of lost-time claim. The date of indemnity and medical claims were obtained from the compensation carrier. Time intervals were created based upon data of entrance into the study until date of lost-time claim. If a company had repeated lost time events, a new interval began after the date of the last lost-time claim. Incidence and frequency of medical claims during the intervals was calculated. Proportional hazards regression was used to model the time to lost-time claim event intervals. The effect of medical claims on risk of lost-time injury was evaluated by estimating hazard ratios (HR) and 95% confidence intervals (CI) as a function of injury rate. Each claim was considered to be independent of prior claims. The sandwich estimate was used to account for within company correlation and for its more robust estimates. The models included potentially confounding covariates of union status, company size, and hours worked.
For the fourth and final hypothesis, our goal was to determine the association of safety and health professional contact on risk of incidence of lost-time claim. The date of indemnity claims and safety and health (S &H) professional contact with the company were obtained from the compensation carrier. Time intervals were created based upon date of entrance into the study until the date of a lost-time claim. If a company had repeated lost-time events, a new interval began after the date of the last lost-time claim. Incidence and frequency of S&H professional contact with the member during the intervals was calculated. Proportional hazards regression was used to model the time to lost-time claim event intervals. The effect of S&H professional contact on risk of lost-time injury were evaluated by estimating hazard ratios (HR) and 95% confidence intervals (CI) as a function of injury rate. Each claim was considered to be independent of prior claims. The sandwich estimate was used to account for within company correlation and for its more robust estimates. The models included potentially confounding covariates of union status, company size, and hours worked.
Results
Hypothesis One illustrated a lower rate of injury for those companies using a drug testing program. Compared to no testing, results respectively were RR=0.85 (CI=0.72-1.0) and RR=0.97 (CI=0.86-1.10) for overall injuries, and RR=0.78 (CI=0.60-1.03) and RR=1.01 (CI=0.86-1.19) for lost-time injuries. Analysis by specific trades revealed significant reductions, as great as 60% for some trades. Significantly lower rates were seen in both union and non-union companies with testing programs. Major injury event and injury type categories also had lower rates when testing programs were used.
For Hypothesis Two, companies were categorized as having a bad attitude or were not yet rated. Compared to good, results for these categories, respectively, were RR=0.94 (CI=0.74-1.19) and RR=1.11 (CI=1.03-1.21) for overall injuries, and RR=1.15 (CI=0.85-1.55) and RR=1.13 (CI=0.99-1.28) for lost-time injuries. In all categories of claims, we observed increased rate of injury claims for companies during the time that they had not been evaluated by a safety professional. Analysis by specific trades revealed some very significant increases in rate, for both categories of companies that had not yet been rated and companies with a poor rating. Prior to contact with a safety professional, we also observed increased injury rates for many injury mechanism, injury type, and claim dollar value categories.
Hypothesis Three revealed that, compared to experiencing 0-1 claims, increased risk occurred with experiencing 2-3 claims (HR=1.25, CI=1.32- 1.75), 4-6 claims (HR=1.36, CI=1.19- 1.56), and 7 or more claims (HR=1.52, CI=1.12- 1.39). Companies with a higher premium size were associated with greater risk of a loss time claim, as were union compaines With Hypothesis Four, compared to experiencing no contact, reduced risk occurred with experiencing one contact (HR=0.77, CI=0.67-0.88) and two contacts (HR=0.63, CI=0.55-0.74). Once companies reached the highest category of contacts, three or more, there was no longer a significant reduction in risk (HR= 1.06, CI= 0.92-1.22). Companies with a higher premium size were associated with greater risk of a loss time claim, as were union companies
Conclusions
The results indicate drug-testing programs may reduce injury rates in this population; however variations in a drug testing program’s effect and magnitude must be considered. Results indicate subjective rating of attitude and commitment from a single visit may not be indicative of injury risk when examining basic injury trends, but may be more predictive when broken down by trade. However, workers were at increased risk of overall injuries, lost-time injuries, and medical injuries during the period prior to the contact with the health and safety professional. The contact of a S & H professional with a company is associated with decreased risk of severe injury claim, compared to no contact. There appears to be an association between frequency of minor injuries and incidence of severe injury.
Description
University of Minnesota Ph.D. dissertation. June 2012. Major: Environmental Health. Advisor: Bruce H. Alexander. 1 computer file (PDF); xi, 116 pages, appendices A-C.
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Schofield, Katherine Elizabeth. (2012). Risk factors for injuries in small and medium sized construction companies. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/154342.
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