Exploring Study Designs for Evaluation of Interventions Aimed to Reduce Occupational Diseases and Injuries

摘要

Abstract Effective interventions to reduce work-related exposures are available for many types of work-related diseases or injuries. However, knowledge of the impact of these interventions on injury or disease outcomes is scarce due to practical and methodological reasons. Study designs are considered for the evaluation of occupational health interventions on occupational disease or injury. Latency and frequency of occurrence of the health outcomes are two important features when designing an evaluation study with occupational disease or occupational injury as an outcome measure. Controlled evaluation studies—giving strong indications for an intervention effect—seem more suitable for more frequently occurring injuries or diseases. Uncontrolled evaluation time or case series studies are an option for evaluating less frequently occurring injuries or diseases. Interrupted time series offer alternatives to experimental randomized controlled trials to give an insight into the effectiveness of preventive actions in the work setting to decision and policy makers. Keywords interventions ; occupational diseases ; study designs prs.rt("abs_end"); 1. Introduction The worldwide burden of occupational diseases(ODs) and injuries is high [1] ; although, there are large variations in and between countries in ODs incidences [2] . For instance, in The Netherlands the annual incidence of occupational diseases varies between 0.3% (physician reported) and 5.7% (workers reported) [3] . Global estimates of ODs economic costs vary between 1.8% and 6.0% of gross domestic product [4] . In principle, ODs can be prevented by means of control measures at worksites. However, the majority of control measures are not evaluated in terms of reductions in ODs [2] . Barriers against controlled trials of interventions are methodological (e.g., the infrequent occurrence of ODs), practical (e.g., too difficult to perform in practice and costly to intervene across a large enough workers' population), or organizational (workplace restructurings during interventions) [5] . To overcome some of these barriers, the choice for an optimal study design should take into account the setting and context of the workers' population (job, sector of industry), application of the intervention (worker, company, sector, national), and outcome measure (expected frequency of disease or injury given a certain time frame). The use of workers' health surveillance data or existing databases like disease or injury registries can provide opportunities to evaluate interventions at company, sectorial, or national level. Registries of ODs are often maintained for regulatory or compensational reasons, but also offer the possibility of evaluating the impact of interventions on a wider scale than company level. However, the feasibility of existing databases depends strongly on the type of intervention and type of disease or injury outcome and requires careful study design. In this short communication we focus on the choice of potential study designs to evaluate the effectiveness of interventions on ODs. Ideally, interventions aimed to reduce ODs should have a proven impact on exposures to hazardous agents and work demands (e.g., based on efficacy studies) and be attuned to the exposed worker’s population and work setting (e.g., through participatory approaches or qualitative research) first before performing studies to evaluate the effectiveness on diseases or injuries. The aim of this paper is: (1) to explore study designs that are potentially useful to evaluate preventive interventions with ODs as an outcome measure; and (2) to provide purposively selected examples of the application of these study designs. 2. Materials and methods Latency and frequency of occurrence of occupational injuries and diseases were considered to be important aspects to take into account in study designs for the evaluation of ODs interventions [6] . In this short communication, shorter latency was, arbitrarily, defined as an interval of ≤ 12 months between exposure to risk factors and occupational diseases and zero for occupational injuries; longer latency was defined in terms of > 12 months for occupational diseases. The frequency with which a disease or injury occurs in a population over a time period was, arbitrarily, defined as lower at ≤ 5% and consequently higher with > 5%. Consequently, four quadrants of ODs outcomes were explored: higher frequency–shorter latency, higher frequency–longer latency, lower frequency–shorter latency, and lower frequency–longer latency. Alongside the four ODs quadrants for possible study designs, a number of applicable Hill's [7] viewpoints were used for prioritizing the different study designs as a means to assess the capability of establishing an ODs intervention effect, i.e., experimental, association, biological gradient, temporality, analogy, specificity, plausibility, consistency, and coherence. The ranking for detecting possible intervention effects alongs