Reviewers noted that a sensitivity analysis of the premium rate that was assumed for the 1991-95 period in the absence of the intervention would have improved confidence in the estimates of financial savings but this was not performed. The reader is not given any information about the consistency of the workforce over the period, although payroll gradually increased by 13 per cent from 1990-92 and then subsequently levelled off suggesting that no major changes took place. As in the case of Alsop and LeCouteur’s analysis, reporting of the longer-term trend in premium rates, and statistical analysis of the difference in rate changes between this hospital and others, would have allowed firmer conclusions.
4.3.4 Summary of results in studies of voluntary OHSMSs The studies involving voluntary OHSMSs were varied in nature. Two (Alsop and LeCouteur, 1999; Yassi, 1998) were descriptions of OHSMSs implemented in single workplaces (a hospital and a municipal government) and reported economic benefits. A third (Edkins, 1998) investigated the effect of an airline safety program (INDICATE) on a regional airline worksite compared to a control worksite and described the effect on safety culture, employees’ perceptions of risk, employee reporting of hazards and actions taken. The fourth (Pearse, 2002) described a community intervention in which small and medium-sized metal fabrication companies were recruited into a program involving development and dissemination of OHSMS guidelines, group networking meetings and audits during and at the conclusion of the program, with the companies’ progress in implementing the OHSMS being the major focus.
All four studies reported positive effects on their outcomes of interest. In spite of including some quantitative data, these studies were primarily descriptive in nature. Only Edkins reported any statistical analysis. The studies were all assigned a methodological quality rating of Moderate (moderate limitations), as none were entirely free of methodological shortcomings which could result in some bias in the results. None of the papers’ authors attempted to situate their results (for example, their premium rates) within longer term trends, to give a more comprehensive picture of the nature of the change before and after the implementation of OHSMS. Nor were their study samples representative of a larger population of worksites/workers. As a consequence, the results of these studies cannot with confidence be generalized.
4.4 Effectiveness of mandatory OHSMSs One approach to the implementation of OHSMSs is through regulatory mechanisms. Five studies of the evaluation of mandatory OHSMSs remained after quality assessment (summarized in Table 4.4.1). Three of the studies were based on the Norwegian regulations on Internal Control (IC) of health, safety, and the environment (Nytro et al., 1998; Saksvik and Nytro, 1996; Torp et al., 2000) and two focused on Canadian provincial regulations which included systematic occupational health and safety (OHS) approaches
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