Cochrane method for systematic review and meta-analysis of interventions to prevent occupational noise-induced hearing loss - abridged.

PURPOSE: Assess the effect of non-pharmaceutical interventions at work on noise exposure or occupational hearing loss compared to no or alternative interventions. RESEARCH STRATEGIES: Pubmed, Embase, Web of Science, OSHupdate, Cochrane Central and Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched. SELECTION CRITERIA: Randomized Controlled Trials (RCT), Controlled Before-After studies (CBA) and Interrupted Time-Series studies (ITS) evaluating engineering controls, administrative controls, personal hearing protection devices, and hearing surveillance were included. Case studies of engineering controls were collected. DATA ANALYSIS: Cochrane methods for systematic reviews, including meta-analysis, were followed. RESULTS: 29 studies were included. Stricter legislation can reduce noise levels by 4.5 dB(A) (very low-quality evidence). Engineering controls can immediately reduce noise (107 cases). Eleven RCTs and CBA studies (3725 participants) were evaluated through Hearing Protection Devices (HPDs). Training of earplug insertion reduces noise exposure at short term follow-up (moderate quality evidence). Earmuffs might perform better than earplugs in high noise levels but worse in low noise levels (very low-quality evidence). HPDs might reduce hearing loss at very long-term follow-up (very low-quality evidence). Seventeen studies (84028 participants) evaluated hearing loss prevention programs. Better use of HPDs might reduce hearing loss but other components not (very low-quality evidence). CONCLUSION: Hearing loss prevention and interventions modestly reduce noise exposure and hearing loss. Better quality studies and better implementation of noise control measures and HPDs is needed.

Cochrane method for systematic review and meta-analysis of interventions to prevent occupational noise-induced hearing loss - abridged / Revisão sistemática e metanálise Cochrane de intervenções para prevenção de perda auditiva ocupacional induzida por ruído - abreviada

ABSTRACT Purpose Assess the effect of non-pharmaceutical interventions at work on noise exposure or occupational hearing loss compared to no or alternative interventions. Research strategies Pubmed, Embase, Web of Science, OSHupdate, Cochrane Central and Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched. Selection criteria Randomized Controlled Trials (RCT), Controlled Before-After studies (CBA) and Interrupted Time-Series studies (ITS) evaluating engineering controls, administrative controls, personal hearing protection devices, and hearing surveillance were included. Case studies of engineering controls were collected. Data analysis Cochrane methods for systematic reviews, including meta-analysis, were followed. Results 29 studies were included. Stricter legislation can reduce noise levels by 4.5 dB(A) (very low-quality evidence). Engineering controls can immediately reduce noise (107 cases). Eleven RCTs and CBA studies (3725 participants) were evaluated through Hearing Protection Devices (HPDs). Training of earplug insertion reduces noise exposure at short term follow-up (moderate quality evidence). Earmuffs might perform better than earplugs in high noise levels but worse in low noise levels (very low-quality evidence). HPDs might reduce hearing loss at very long-term follow-up (very low-quality evidence). Seventeen studies (84028 participants) evaluated hearing loss prevention programs. Better use of HPDs might reduce hearing loss but other components not (very low-quality evidence). Conclusion Hearing loss prevention and interventions modestly reduce noise exposure and hearing loss. Better quality studies and better implementation of noise control measures and HPDs is needed.

RESUMO Objetivo Avaliar o efeito de intervenções no trabalho sobre a exposição ao ruído ou a perda auditiva em comparação com ausência ou intervenções alternativas. Estratégia de pesquisa Buscas em Pubmed, Embase, Web of Science, OSHupdate, Cochrane Central e CINAHL. Critérios de seleção Incluídos ensaios clínicos randomizados (ECR), estudos controlados pré/pós-intervenção (ECPPI) e estudos de séries temporais interrompidas (SIT) avaliando controles de engenharia, administrativos, equipamentos de proteção auditiva (EPAs) e vigilância auditiva. Coletados estudos de caso de engenharia. Análise dos dados Cochrane para revisões sistemáticas, incluindo metanálise. Resultados Foram incluídos 29 estudos. Legislação mais rigorosa pode reduzir níveis de ruído em 4,5 dB(A) (evidência de qualidade muito baixa). Controles de engenharia podem reduzir imediatamente o ruído (107 casos). Onze ECR e ECPPI (3.725 participantes) avaliaram EPAs. Treinamento para inserção do EPA reduz a exposição ao ruído no acompanhamento de curto prazo (evidência de qualidade moderada). Protetores tipo concha podem ter desempenho melhor do que protetores de inserção em níveis altos de ruído, mas piores em níveis mais baixos (evidência de qualidade muito baixa). EPAs podem reduzir a perda auditiva no acompanhamento de muito longo prazo (evidência de qualidade muito baixa). Dezessete estudos (84.028 participantes) avaliaram programas de prevenção de perdas auditivas. Um melhor uso do EPA pode reduzir a perda auditiva, mas outros componentes não (evidência de qualidade muito baixa). Conclusão As intervenções para prevenção da perda auditiva reduzem modestamente a exposição ao ruído e a perda auditiva. Estudos de melhor qualidade e melhor implementação de medidas de controle de ruído e EPA são necessários.

Interventions to prevent occupational noise-induced hearing loss.

BACKGROUND: This is the second update of a Cochrane Review originally published in 2009. Millions of workers worldwide are exposed to noise levels that increase their risk of hearing disorders. There is uncertainty about the effectiveness of hearing loss prevention interventions. OBJECTIVES: To assess the effectiveness of non-pharmaceutical interventions for preventing occupational noise exposure or occupational hearing loss compared to no intervention or alternative interventions. SEARCH METHODS: We searched the CENTRAL; PubMed; Embase; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; and OSH UPDATE to 3 October 2016. SELECTION CRITERIA: We included randomised controlled trials (RCT), controlled before-after studies (CBA) and interrupted time-series (ITS) of non-clinical interventions under field conditions among workers to prevent or reduce noise exposure and hearing loss. We also collected uncontrolled case studies of engineering controls about the effect on noise exposure. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study eligibility and risk of bias and extracted data. We categorised interventions as engineering controls, administrative controls, personal hearing protection devices, and hearing surveillance. MAIN RESULTS: We included 29 studies. One study evaluated legislation to reduce noise exposure in a 12-year time-series analysis but there were no controlled studies on engineering controls for noise exposure. Eleven studies with 3725 participants evaluated effects of personal hearing protection devices and 17 studies with 84,028 participants evaluated effects of hearing loss prevention programmes (HLPPs). Effects on noise exposure Engineering interventions following legislationOne ITS study found that new legislation in the mining industry reduced the median personal noise exposure dose in underground coal mining by 27.7 percentage points (95% confidence interval (CI) -36.1 to -19.3 percentage points) immediately after the implementation of stricter legislation. This roughly translates to a 4.5 dB(A) decrease in noise level. The intervention was associated with a favourable but statistically non-significant downward trend in time of the noise dose of -2.1 percentage points per year (95% CI -4.9 to 0.7, 4 year follow-up, very low-quality evidence). Engineering intervention case studiesWe found 12 studies that described 107 uncontrolled case studies of immediate reductions in noise levels of machinery ranging from 11.1 to 19.7 dB(A) as a result of purchasing new equipment, segregating noise sources or installing panels or curtains around sources. However, the studies lacked long-term follow-up and dose measurements of workers, and we did not use these studies for our conclusions. Hearing protection devicesIn general hearing protection devices reduced noise exposure on average by about 20 dB(A) in one RCT and three CBAs (57 participants, low-quality evidence). Two RCTs showed that, with instructions for insertion, the attenuation of noise by earplugs was 8.59 dB better (95% CI 6.92 dB to 10.25 dB) compared to no instruction (2 RCTs, 140 participants, moderate-quality evidence). Administrative controls: information and noise exposure feedbackOn-site training sessions did not have an effect on personal noise-exposure levels compared to information only in one cluster-RCT after four months' follow-up (mean difference (MD) 0.14 dB; 95% CI -2.66 to 2.38). Another arm of the same study found that personal noise exposure information had no effect on noise levels (MD 0.30 dB(A), 95% CI -2.31 to 2.91) compared to no such information (176 participants, low-quality evidence). Effects on hearing loss Hearing protection devicesIn two studies the authors compared the effect of different devices on temporary threshold shifts at short-term follow-up but reported insufficient data for analysis. In two CBA studies the authors found no difference in hearing loss from noise exposure above 89 dB(A) between muffs and earplugs at long-term follow-up (OR 0.8, 95% CI 0.63 to 1.03 ), very low-quality evidence). Authors of another CBA study found that wearing hearing protection more often resulted in less hearing loss at very long-term follow-up (very low-quality evidence). Combination of interventions: hearing loss prevention programmesOne cluster-RCT found no difference in hearing loss at three- or 16-year follow-up between an intensive HLPP for agricultural students and audiometry only. One CBA study found no reduction of the rate of hearing loss (MD -0.82 dB per year (95% CI -1.86 to 0.22) for a HLPP that provided regular personal noise exposure information compared to a programme without this information.There was very-low-quality evidence in four very long-term studies, that better use of hearing protection devices as part of a HLPP decreased the risk of hearing loss compared to less well used hearing protection in HLPPs (OR 0.40, 95% CI 0.23 to 0.69). Other aspects of the HLPP such as training and education of workers or engineering controls did not show a similar effect.In three long-term CBA studies, workers in a HLPP had a statistically non-significant 1.8 dB (95% CI -0.6 to 4.2) greater hearing loss at 4 kHz than non-exposed workers and the confidence interval includes the 4.2 dB which is the level of hearing loss resulting from 5 years of exposure to 85 dB(A). In addition, of three other CBA studies that could not be included in the meta-analysis, two showed an increased risk of hearing loss in spite of the protection of a HLPP compared to non-exposed workers and one CBA did not. AUTHORS' CONCLUSIONS: There is very low-quality evidence that implementation of stricter legislation can reduce noise levels in workplaces. Controlled studies of other engineering control interventions in the field have not been conducted. There is moderate-quality evidence that training of proper insertion of earplugs significantly reduces noise exposure at short-term follow-up but long-term follow-up is still needed.There is very low-quality evidence that the better use of hearing protection devices as part of HLPPs reduces the risk of hearing loss, whereas for other programme components of HLPPs we did not find such an effect. The absence of conclusive evidence should not be interpreted as evidence of lack of effectiveness. Rather, it means that further research is very likely to have an important impact.

Interventions to prevent occupational noise-induced hearing loss: a Cochrane systematic review.

OBJECTIVE: To assess the effectiveness of interventions for preventing occupational noise exposure or hearing loss compared to no intervention or alternative interventions. DESIGN: We searched biomedical databases up to 25 January 2012 for randomized controlled trials (RCT), controlled before-after studies and interrupted time-series of hearing loss prevention among workers exposed to noise. STUDY SAMPLE: We included 19 studies with 82 794 participants evaluating effects of hearing loss prevention programs (HLPP). The overall quality of studies was low to very low, as rated using the GRADE approach. RESULTS: One study of stricter legislation showed a favorable effect on noise levels. Three studies, of which two RCTs, did not find an effect of a HLPP. Four studies showed that better use of hearing protection devices in HLPPs decreased the risk of hearing loss. In four other studies, workers in a HLPP still had a 0.5 dB greater hearing loss at 4 kHz (95% CI - 0.5 to 1.7) than non-exposed workers. In two similar studies there was a substantial risk of hearing loss in spite of a HLPP. CONCLUSIONS: Stricter enforcement of legislation and better implementation of HLPPs can reduce noise levels in workplaces. Better evaluations of technical interventions and long-term effects are needed.

Interventions to prevent occupational noise-induced hearing loss.

BACKGROUND: Millions of workers worldwide are exposed to noise levels that increase their risk of hearing impairment. Little is known about the effectiveness of hearing loss prevention interventions. OBJECTIVES: To assess the effectiveness of non-pharmaceutical interventions for preventing occupational noise exposure or occupational hearing loss compared to no intervention or alternative interventions. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; and OSH update to 25 January 2012. SELECTION CRITERIA: We included randomised controlled trials (RCT), controlled before-after studies (CBA) and interrupted time-series (ITS) of non-clinical hearing loss prevention interventions under field conditions among workers exposed to noise. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study eligibility and risk of bias and extracted data. MAIN RESULTS: We included 25 studies. We found no controlled studies on engineering controls for noise exposure but one study evaluated legislation to reduce noise exposure in a 12-year time-series analysis. Eight studies with 3,430 participants evaluated immediate and long-term effects of personal hearing protection devices (HPDs) and sixteen studies with 82,794 participants evaluated short and long-term effects of hearing loss prevention programmes (HLPPs). The overall quality of studies was low to very low.The one ITS study that evaluated the effect of new legislation in reducing noise exposure found that the median noise level decreased by 27.7 dB(A) (95% confidence interval (CI) -36.1 to -19.3 dB) immediately after the implementation of stricter legislation and that this was associated with a favourable downward trend in time of -2.1 dB per year (95% CI -4.9 to 0.7).Hearing protection devices attenuated noise with about 20 dB(A) with variation among brands and types but for ear plugs these findings depended almost completely on proper instruction of insertion. Noise attenuation ratings of hearing protection under field conditions were consistently lower than the ratings provided by the manufacturers.One cluster-RCT compared a three-year information campaign as part of a hearing loss prevention programme for agricultural students to audiometry only with three and 16-year follow-up but there were no significant differences in hearing loss. Another study compared a HLPP, which provided regular personal noise exposure information, to a programme without this information in a CBA design. Exposure information was associated with a favourable but non-significant reduction of the rate of hearing loss of -0.82 dB per year (95% CI -1.86 to 0.22). Another cluster-RCT evaluated the effect of extensive on-site training sessions and the use of personal noise-level indicators versus information only on noise levels but did not find a significant difference after four months follow-up (Mean Difference (MD) -0.30 dB(A) (95%CI -3.95 to 3.35).There was very low quality evidence in four very long-term studies, that better use of HPDs as part of a HLPP decreased the risk of hearing loss compared to less well used hearing protection in HLPPs. Other aspects of the HLPP such as training and education of workers or engineering controls did not show a similar effect.In four long-term studies, workers in a HLPP still had a 0.5 dB greater hearing loss at 4 kHz than workers that were not exposed to noise (95% CI -0.5 to 1.7) which is about the level of hearing loss caused by exposure to 85 dB(A). In addition, two other studies showed substantial risk of hearing loss in spite of the protection of a HLPP compared to non-exposed workers. AUTHORS' CONCLUSIONS: There is low quality evidence that implementation of stricter legislation can reduce noise levels in workplaces. Even though case studies show that substantial reductions in noise levels in the workplace can be achieved, there are no controlled studies of the effectiveness of such measures. The effectiveness of hearing protection devices depends on training and their proper use. There is very low quality evidence that the better use of hearing protection devices as part of HLPPs reduces the risk of hearing loss, whereas for other programme components of HLPPs we did not find such an effect. Better implementation and reinforcement of HLPPs is needed. Better evaluations of technical interventions and long-term effects are needed.

Interventions to prevent occupational noise induced hearing loss.

BACKGROUND: Millions of workers worldwide are exposed to noise levels that increase their risk of hearing impairment. Little is known about the effectiveness of hearing loss prevention interventions. OBJECTIVES: To assess the effectiveness of non-pharmaceutical interventions for preventing occupational noise exposure or occupational hearing loss compared to no intervention or alternative interventions. SEARCH STRATEGY: We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library issue 4, 2008); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; NIOSHTIC, CISDOC and mRCT to 15 December 2008. SELECTION CRITERIA: Randomised controlled trials, controlled before-after studies and interrupted time series (ITS) of non-clinical hearing loss prevention interventions under field conditions among workers exposed to noise. DATA COLLECTION AND ANALYSIS: Two authors (EK, JV) independently assessed study eligibility and trial quality and extracted data. MAIN RESULTS: Twenty-one studies were included. One study evaluated a strategy to reduce noise exposure. Fourteen studies with 75,672 participants evaluated hearing loss prevention programmes (HLPPs), and six studies with 169 participants evaluated hearing protection. The overall quality of studies was low.One ITS study evaluated the effect of new legislation in reducing noise exposure. It found that the median noise level decreased by 27.7 dB(A) (95% confidence interval (CI) -36.1 to -19.3 dB) with a change in trend in time of -2.1 dB per year (95% CI -4.9 to 0.7).A hearing protection study in army recruits compared those exposed to impulse noise with non-exposed recruits. The odds ratio (OR) for hearing loss was 3.0 (95% CI 1.1 to 8.0) despite hearing protection. In four studies, workers in a HLPP had a 0.5 dB HL greater hearing loss at 4 kHz than non-noise exposed workers (95% CI -0.5 to 1.7). In one study, the hazard ratio of hearing loss was 3.8 (95% CI 2.7 to 5.3) for workers exposed to noise compared to non-exposed workers.In three studies, a high quality HLPP had a lower risk of hearing loss than lower quality programmes.Noise attenuation ratings of hearing protection under field conditions were consistently lower than the ratings provided by the manufacturers. AUTHORS' CONCLUSIONS: There is low quality evidence that legislation can reduce noise levels in workplaces.The effectiveness of hearing protection devices depends on their proper use. There is contradictory evidence that HLPPs are effective in the long-term. Even though case studies show that substantial reductions can be achieved, there is no evidence that this is realised in practice. Better implementation and reinforcement is needed.Better evaluations of technical interventions and long-term effects are needed. Audiometric and noise measurement data are potentially valuable for such studies.