In reflecting on his career, Archie Cochrane once said that he felt it was a pity that he was mainly remembered for his work on randomised controlled trials (RCTs). He actually felt more proud of the research he had done on behalf of workers in British coal mines. Based on his work, dust levels in coal mines have been lowered considerably, reducing the risk of pneumoconiosis. There have been improvements in many other occupational safety and health (OSH) statistics, such as injury rates and exposures to chemical agents, but there are also OSH problems for which the statistics have not shown a decline. Occupational hearing loss is still reported among the most frequent occupational diseases in many countries. Around the world, workers and employers struggle with problems such as disability related to back pain and other musculoskeletal problems. And in health care, we still cannot fully protect workers from the risks of contracting infectious diseases from their work.
We know there are still many gaps in the evidence base for preventing occupational diseases, but what is available today can impact and improve the preventive potential of health and safety interventions at work. OSH issues are usually dominated by negotiations between unions, employers, and government representatives. In this process, evidence from RCTs does not always play a big role. However, Cochrane Review authors have analysed many valuable studies that can and should change practice.
Let's take a look at the review of the effects of blunt needles in surgery to prevent needle stick injuries and the contraction of serious infectious diseases. Studies report varying results, but the synthesis of ten RCTs in a meta-analysis shows a more than 50% reduction of needle stick injuries with blunt needles. These needles cannot be used in all types of operations, but where they can be used they should be used. This is the recommendation of the US Centers for Disease Control and Prevention (CDC), the US Food and Drug Administration (FDA), and the National Institute for Occupational Safety and Health (NIOSH), based on this systematic review.
Another Cochrane Review acknowledges that hearing loss prevention programmes are difficult to evaluate in RCTs. As preventive measures are mandatory, using a no-intervention or a minor-intervention control group is difficult to defend. However, non-randomised studies have successfully compared workers that are exposed and covered by a prevention programme with workers who are not exposed to noise. These studies show that workers still sustain hearing loss in spite of the prevention programmes. When in 2010 the US Secretary of Labor proposed more stringent implementation of preventive measures, NIOSH was one of the stakeholders that cited the Cochrane Review in support of the proposed change.
Prevention of hearing loss relies heavily on providing hearing protection, most commonly earplugs, to those who are exposed to noise. However, the Cochrane Review shows that without personal instruction, protection is only half of what it should be, based on an RCT dating back to 1991. About half of those who try to insert earplugs do so incorrectly without proper instruction. This includes two of us (JV and TM). Thus a large proportion of exposed workers are not sufficiently protected, which might explain the mediocre results of hearing loss prevention efforts. Mandatory instruction or mandatory testing of the fit of the plugs could help to overcome this. Controlling the exposure, meanwhile, remains the preferred recommended intervention.
Many OSH professionals believe that correct body posture while lifting will prevent back pain. The authors of the Cochrane Review on training and advice to prevent back pain found nine RCTs and nine cohort studies, none of which reported a beneficial effect of training on back pain. Admittedly it is always more difficult to show that an intervention is not effective than to show it is effective. Especially with preventive interventions, a small beneficial effect can still be relevant at the population level. Nevertheless, the lack of an effect across all included studies leaves little hope that future studies would arrive at a contrary conclusion. We believe that this evidence should be used more commonly by OSH practitioners. Many are initially reluctant to accept this finding as they generally believe training to be the hallmark of OSH. But after a closer look, they hopefully will become proponents of interventions that target exposure control. Even where it is not possible to change the load being lifted, there are preventive options other than training and instruction. However, specific evidence for their effectiveness has not yet been summarised in a systematic review.
This editorial is accompanied by a Cochrane Library Special Collection highlighting the work of the Cochrane Collaboration in OSH. Another 13 reviews on interventions for preventing occupational diseases are in preparation. We would like to encourage all to get involved by reading these reviews and protocols, submitting comments, suggesting topics for future reviews, and most importantly, putting the evidence to good use.
Jos Verbeek1; Thais C Morata2, Jani Ruotsalainen3, Harri Vainio4
1Jos Verbeek (firstname.lastname@example.org), Co-ordinating Editor, Cochrane Occupational Safety and Health Review Group, Finnish Institute of Occupational Health, Kuopio, Finland; 2Thais Morata (email@example.com), National Institute for Occupational Safety and Health, Cincinnati, USA; 3Jani Ruotsalainen (firstname.lastname@example.org), Managing Editor, Cochrane Occupational Safety and Health Review Group, Finnish Institute of Occupational Health, Kuopio, Finland; 4Harri Vainio (email@example.com), General director, Finnish Institute of Occupational Health, Helsinki, Finland.
How to cite: Verbeek J, Morata TC, Ruotsalainen J, Vainio H. Prevention of occupational diseases: implementing the evidence [editorial]. Cochrane Database of Systematic Reviews 2013 30 April;4:ED000056. dx.doi.org/10.1002/14651858.ED000056
1. Cochrane AL, Blythe M. One man's medicine: an autobiography of Professor Archie Cochrane. London: BMJ (Memoir Club), 1989.
2. Creely KS, Cowie H, Van TM, Kromhout H, Tickner J, Cherrie JW. Trends in inhalation exposure: a review of the data in the published scientific literature. Annals of Occupational Hygiene 2007;51(8):665-78. dx.doi.org/10.1093/annhyg/mem050
3. Parantainen A, Verbeek J, Lavoie M, Pahwa M. Blunt versus sharp suture needles for preventing percutaneous exposure incidents in surgical staff. Cochrane Database Systematic Reviews 2011(11):CD009170. dx.doi.org/10.1002/14651858.CD009170.pub2
4. US Food and Drug Administration. FDA, NIOSH and OSHA Joint Safety Communication: Blunt-tip surgical suture needles reduce needlestick injuries and the risk of subsequent bloodborne pathogen transmission to surgical personnel. http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm305757.htm (accessed 8 April 2013)
5. Verbeek JH, Kateman E, Morata TC, Dreschler WA, Mischke C. Interventions to prevent occupational noise-induced hearing loss. Cochrane Database of Systematic Reviews 2012;10:CD006396. dx.doi.org/10.1002/14651858.CD006396.pub3
6. Schulte P. Comments of the National Institute for Occupational Safety and Health on the Occupational Safety and Health Proposed Interpretation of Provisions for Feasible Administrative or Engineering Controls of Occupational Noise. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 2010.
7. Verbeek J, Martimo KP, Karppinen J, Kuijer PP, Viikari-Juntura E, Takala EP. Manual material handling advice and assistive devices for preventing and treating back pain in workers. Cochrane Database of Systematic Reviews 2011;7:CD005958. dx.doi.org/10.1002/14651858.CD005958.pub3
Competing interests: The authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available upon request) and declare (1) no receipt of payment or support in kind for any aspect of the article; (2) that JV and JR are paid by the Finnish Institute of Occupational Health for their work as Co-ordinating Editor and Managing Editor, respectively, of the Cochrane Occupational Safety and Health Review Group, that JV is reimbursed for travelling to speak at meetings about Cochrane Collaboration activities, but there are no other financial relationships with any entities that have an interest related to the submitted work; and (3) that there are no other relationships or activities that could be perceived as having influenced, or giving the appearance of potentially influencing, what was written in the submitted work.
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Contact the Editor in Chief, Dr David Tovey (firstname.lastname@example.org): Feedback on this editorial and proposals for future editorials are welcome.