Association between night-shift work, sleep quality and health-related quality of life: a cross-sectional study among manufacturing workers in a middle-income setting.

OBJECTIVES: Night-shift work may adversely affect health. This study aimed to determine the impact of night-shift work on health-related quality of life (HRQoL), and to assess whether sleep quality was a mediating factor. DESIGN: A cross-sectional study. SETTING: 11 manufacturing factories in Malaysia. PARTICIPANTS: 177 night-shift workers aged 40-65 years old were compared with 317 non-night-shift workers. PRIMARY AND SECONDARY OUTCOMES: Participants completed a self-administered questionnaire on socio-demographics and lifestyle factors, 12-item Short Form Health Survey V.2 (SF-12v2) and the Pittsburgh Sleep Quality Index (PSQI). The Baron and Kenny's method, Sobel test and multiple mediation model with bootstrapping were applied to determine whether PSQI score or its components mediated the association between night-shift work and HRQoL. RESULTS: Night-shift work was associated with sleep impairment and HRQoL. Night-shift workers had significantly lower mean scores in all the eight SF-12 domains (p<0.001). Compared with non-night-shift workers, night-shift workers were significantly more likely to report poorer sleep quality, longer sleep latency, shorter sleep duration, sleep disturbances and daytime dysfunction (p<0.001). Mediation analyses showed that PSQI global score mediated the association between night-shift work and HRQoL. 'Subjective sleep quality' (indirect effect=-0.24, SE=0.14 and bias corrected (BC) 95% CI -0.58 to -0.01) and 'sleep disturbances' (indirect effect=-0.79, SE=0.22 and BC 95% CI -1.30 to -0.42) were mediators for the association between night-shift work and physical well-being, whereas 'sleep latency' (indirect effect=-0.51, SE=0.21 and BC 95% CI -1.02 to -0.16) and 'daytime dysfunction' (indirect effect=-1.11, SE=0.32 and BC 95% CI -1.86 to -0.58) were mediators with respect to mental well-being. CONCLUSION: Sleep quality partially explains the association between night-shift work and poorer HRQoL. Organisations should treat the sleep quality of night-shift workers as a top priority area for action to improve their employees' overall wellbeing.

Association between night-shift work, sleep quality and metabolic syndrome.

OBJECTIVES: Occupational factors, particularly night-shift work, are attracting growing interest as a possible determinant of metabolic syndrome (MetS). This study aimed to determine the association between night-shift work and MetS, and assess whether sleep quality is a mediating factor. METHODS: A cross-sectional study was conducted among Malaysian manufacturing workers, aged 40-65 years old. They completed a self-administered questionnaire on sociodemographics, lifestyle and family history, and the Pittsburgh Sleep Quality Index (PSQI) questionnaire. Waist circumference, blood pressure, fasting blood sugar, triglycerides and high-density lipoprotein levels were measured. Baron and Kenny's method, Sobel test and multiple mediation models with bootstrapping were used to determine whether the PSQI global score or its components mediated the association between night-shift work and MetS. RESULTS: Of the 494 participants, 177 (36%) worked night shift and 51% were men. The prevalence of MetS was 37%. Night-shift work was independently associated with a twofold increase in the risk of MetS (adjusted OR: 1.92, 95% CI 1.24 to 2.97). However, the association between night-shift work and MetS did not appear to be modified by sex. Night-shift workers also reported significantly poorer sleep quality, longer sleep latency, shorter sleep duration, sleep disturbances and daytime dysfunction. Robust mediation analysis nonetheless showed that neither PSQI global score nor its components mediated the association between night-shift work and MetS. CONCLUSION: Early screening and management of MetS and the development of programmes to improve sleep quality should be carried out among night-shift workers. Future research should investigate other modifiable mediators linking night-shift work and MetS.

Association between pain catastrophising and musculoskeletal disorders is modified by past injuries in Malaysian military recruits.

OBJECTIVES: Pain catastrophising is defined as exaggerated negative thoughts, which can occur during an actual or anticipated painful experience, such as musculoskeletal injuries (MSI) or disorders (MSD). The aims of this study are to examine the association between pain catastrophising and MSI and MSD in Malaysian Army male recruits, and evaluate the effects of past injury. METHODS: A cohort of 611 male Malaysian Army recruits were recruited and followed up at 3 and 6 months. Pain catastrophising, MSD, sociodemographic and work factors were measured using a self-administered questionnaire, and MSI incidence was retrieved from the medical records. Multivariable fixed effects regression was used to model the cumulative incidence of MSD and MSI. RESULTS: Approximately 12% of the recruits were diagnosed with incident MSI and 80% reported incident MSD. Higher pain catastrophising at baseline was associated with higher 6 month MSD risk (adjusted OR (aOR) 1.6 per 1 SD increase of Pain Catastrophising Scale (PCS) scores; 95% CI 1.2 to 2.0), and longitudinally associated with MSD incidence (aOR 1.2, 95% CI 1.1 to 1.4). Pain catastrophising was not associated with MSI incidence (aOR 1.0, 95% CI 0.8 to 1.3). The association between pain catastrophising and self-reported MSD was stronger among recruits with self-reported past injury (p for interaction <0.001). CONCLUSIONS: Pain catastrophising was able to predict symptomatic MSD, and not physician-diagnosed MSI, and these findings are directly related to individual health beliefs. Pain catastrophising has a greater influence on how military recruits perceived their musculoskeletal conditions during training, and efforts to reduce pain catastrophising may be beneficial.

Cultural adaptation and psychometric assessment of Pain Catastrophizing Scale among young healthy Malay-speaking adults in military settings.

PURPOSE: The Pain Catastrophizing Scale (PCS) is designed to assess negative thoughts in response to pain. It is composed of three domains: helplessness, rumination, and magnification. We report on the translation, adaptation, and validation of scores on a Malay-speaking version of the PCS, the PCS-MY. METHOD: Guidelines for the process of cross-cultural adaptations of assessment measures were implemented. A sample of 303 young military recruits participated in the study. Factor structure, reliability, and validity of scores on the PCS-MY were examined. Convergent validity was investigated with the Positive and Negative Affect Scale, Short-form 12 version 2, and Ryff's Psychological Well-being Scale. RESULTS: Most participants were men, ranging in age from 19 to 26. The reliability of the PCS-MY scores was adequate (α = 0.90; mean inter-item correlation = 0.43). Confirmatory factor analysis showed that a modified version of the PCS-MY provided best fit estimates to the sample data. The PCS-MY total score was negatively correlated with mental well-being and positively correlated with negative affect (all ps < 0.001). CONCLUSION: The PCS-MY was demonstrated to have adequate reliability and validity estimates in the study sample.

A comparison of hand-arm vibration syndrome between Malaysian and Japanese workers.

OBJECTIVES: The aim of this study was to investigate the clinical characteristics of HAVS in a tropical environment in comparison with a temperate environment. METHODS: We conducted a series medical examinations among the forestry, construction and automobile industry workers in Malaysia adopting the compulsory medical examination procedure used by Wakayama Medical University for Japanese vibratory tools workers. We matched the duration of vibration exposure and compared our results against the Japanese workers. We also compared the results of the Malaysian tree fellers against a group of symptomatic Japanese tree fellers diagnosed with HAVS. RESULTS: Malaysian subjects reported a similar prevalence of finger tingling, numbness and dullness (Malaysian=25.0%, Japanese=21.5%, p=0.444) but had a lower finger skin temperature (FST) and higher vibrotactile perception threshold (VPT) values as compared with the Japanese workers. No white finger was reported in Malaysian subjects. The FST and VPT of the Malaysian tree fellers were at least as bad as the Japanese tree fellers despite a shorter duration (mean difference=20.12 years, 95%CI=14.50, 25.40) of vibration exposure. CONCLUSIONS: Although the vascular disorder does not manifest clinically in the tropical environment, the severity of HAVS can be as bad as in the temperate environment with predominantly neurological disorder. Hence, it is essential to formulate national legislation for the control of the occupational vibration exposure.

Dose-response relationship between hand-transmitted vibration and hand-arm vibration syndrome in a tropical environment.

OBJECTIVES: The dose-response relationship for hand-transmitted vibration has been investigated extensively in temperate environments. Since the clinical features of hand-arm vibration syndrome (HAVS) differ between the temperate and tropical environment, we conducted this study to investigate the dose-response relationship of HAVS in a tropical environment. METHODS: A total of 173 male construction, forestry and automobile manufacturing plant workers in Malaysia were recruited into this study between August 2011 and 2012. The participants were interviewed for history of vibration exposure and HAVS symptoms, followed by hand functions evaluation and vibration measurement. Three types of vibration doses-lifetime vibration dose (LVD), total operating time (TOT) and cumulative exposure index (CEI)-were calculated and its log values were regressed against the symptoms of HAVS. The correlation between each vibration exposure dose and the hand function evaluation results was obtained. RESULTS: The adjusted prevalence ratio for finger tingling and numbness was 3.34 (95% CI 1.27 to 8.98) for subjects with lnLVD≥20 ln m(2) s(-4) against those <16 ln m(2) s(-4). Similar dose-response pattern was found for CEI but not for TOT. No subject reported white finger. The prevalence of finger coldness did not increase with any of the vibration doses. Vibrotactile perception thresholds correlated moderately with lnLVD and lnCEI. CONCLUSIONS: The dose-response relationship of HAVS in a tropical environment is valid for finger tingling and numbness. The LVD and CEI are more useful than TOT when evaluating the dose-response pattern of a heterogeneous group of vibratory tools workers.

Are psychosocial factors associated with low back pain and work absence for low back pain in an occupational cohort?

OBJECTIVES: To examine the relationship between individual and work-related psychosocial factors and low back pain (LBP) and associated time off work in an occupational cohort. METHODS: A self-administered questionnaire was completed by nurses working across 3 major public hospitals. Participants provided sociodemographic data and information on the occurrence of LBP, time off work, and psychosocial factors. RESULTS: One thousand one hundred eleven participants (response rate 38.6%) were included in the study. Fifty-six percent of participants reported LBP in the previous year. When individual psychosocial factors were examined in the same model, the relationship between somatization and LBP persisted (OR 1.64; 95% confidence interval [CI], 1.35, 2.01). Low job security was also significantly associated with LBP independent of the other work-related factors (OR 0.82; 95% CI, 0.69, 0.98). Of those participants with LBP, 30% reported absence from work due to LBP. When absence from work was examined, negative beliefs (OR 0.97; 95% CI, 0.94, 1.00) and pain catastrophizing (OR 1.33; 95% CI, 1.04, 1.71) were independently associated with time off work, along with low job satisfaction (OR 0.71; 95% CI, 0.51, 0.97) and high job support (OR 1.35; 95% CI, 1.04, 1.75). CONCLUSIONS: Somatization and low job security were found to be independently associated with occupational LBP, whereas negative beliefs, pain catastrophizing, reduced job satisfaction, and high job support were independently related to time off work. Longitudinal studies are needed to determine whether these individual and work-related psychosocial factors predict, or alternatively, are outcomes of pain and time off work associated with LBP.

Physical and psychosocial factors associated with wrist or hand pain among Australian hospital-based nurses.

OBJECTIVE: To assess the personal, physical and psychosocial factors associated with wrist or hand pain in Australian hospital-based nurses. METHODS: Wrist or hand pain, associated disability and sickness absence, demographic, occupational, physical, psychosocial and personal factors among nurses working for three hospitals in Melbourne, Australia, were assessed in a cross-sectional study. Factors associated with wrist or hand pain in the past month were assessed using logistic regression. RESULTS: This analysis was based on 1111 participants. The prevalence of wrist or hand pain in the past month was 15.3%. Repeated movements of the wrist or finger >4 h (OR 2.63, 95% CI 1.80 to 3.84), high job strain (1.54, 1.04 to 2.28), job insecurity (1.55, 1.04 to 2.28), somatisation tendency (2.73, 1.75 to 4.26), pain catastrophising (1.56, 1.03 to 2.37), better mental (0.97, 0.95 to 0.99) and physical (0.96, 0.94-0.98) health and well-being were associated with wrist or hand pain in the past month, after adjusting for possible confounding factors. When all significant factors were examined in the same model, repeated movements of the wrist or finger >4 h (2.50, 1.71 to 3.67), somatisation (2.61, 1.65 to 4.13) and better physical health and well-being (0.96, 0.94 to 0.99) remained independently associated with wrist or hand pain in the past month. CONCLUSIONS: This study highlights that wrist or hand pain is prevalent in hospital nurses. Workplace physical factors and personal factors were associated with wrist or hand pain. Further longitudinal investigation is needed to examine the predictive nature of these factors.

Ergonomic design and training for preventing work-related musculoskeletal disorders of the upper limb and neck in adults.

BACKGROUND: Work-related upper limb and neck musculoskeletal disorders (MSDs) are one of the most common occupational disorders around the world. Although ergonomic design and training are likely to reduce the risk of workers developing work-related upper limb and neck MSDs, the evidence is unclear. OBJECTIVES: To assess the effects of workplace ergonomic design or training interventions, or both, for the prevention of work-related upper limb and neck MSDs in adults. SEARCH METHODS: We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, AMED, Web of Science (Science Citation Index), SPORTDiscus, Cochrane Occupational Safety and Health Review Group Database and Cochrane Bone, Joint and Muscle Trauma Group Specialised Register to July 2010, and Physiotherapy Evidence Database, US Centers for Disease Control and Prevention, the National Institute for Occupational Safety and Health database, and International Occupational Safety and Health Information Centre database to November 2010. SELECTION CRITERIA: We included randomised controlled trials (RCTs) of ergonomic workplace interventions for preventing work-related upper limb and neck MSDs. We included only studies with a baseline prevalence of MSDs of the upper limb or neck, or both, of less than 25%. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed risk of bias. We included studies with relevant data that we judged to be sufficiently homogeneous regarding the intervention and outcome in the meta-analysis. We assessed the overall quality of the evidence for each comparison using the GRADE approach. MAIN RESULTS: We included 13 RCTs (2397 workers). Eleven studies were conducted in an office environment and two in a healthcare setting. We judged one study to have a low risk of bias. The 13 studies evaluated effectiveness of ergonomic equipment, supplementary breaks or reduced work hours, ergonomic training, a combination of ergonomic training and equipment, and patient lifting interventions for preventing work-related MSDs of the upper limb and neck in adults.Overall, there was moderate-quality evidence that arm support with alternative mouse reduced the incidence of neck/shoulder disorders (risk ratio (RR) 0.52; 95% confidence interval (CI) 0.27 to 0.99) but not the incidence of right upper limb MSDs (RR 0.73; 95% CI 0.32 to 1.66); and low-quality evidence that this intervention reduced neck/shoulder discomfort (standardised mean difference (SMD) -0.41; 95% CI -0.69 to -0.12) and right upper limb discomfort (SMD -0.34; 95% CI -0.63 to -0.06).There was also moderate-quality evidence that the incidence of neck/shoulder and right upper limb disorders were not reduced when comparing alternative mouse and conventional mouse (neck/shoulder RR 0.62; 95% CI 0.19 to 2.00; right upper limb RR 0.91; 95% CI 0.48 to 1.72), arm support and no arm support with conventional mouse (neck/shoulder RR 0.67; 95% CI 0.36 to 1.24; right upper limb RR 1.09; 95% CI 0.51 to 2.29), and alternative mouse with arm support and conventional mouse with arm support (neck/shoulder RR 0.58; 95% CI 0.30 to 1.12; right upper limb RR 0.92; 95% CI 0.36 to 2.36).There was low-quality evidence that using an alternative mouse with arm support compared to conventional mouse with arm support reduced neck/shoulder discomfort (SMD -0.39; 95% CI -0.67 to -0.10). There was low- to very low-quality evidence that other interventions were not effective in reducing work-related upper limb and neck MSDs in adults. AUTHORS' CONCLUSIONS: We found moderate-quality evidence to suggest that the use of arm support with alternative mouse may reduce the incidence of neck/shoulder MSDs, but not right upper limb MSDs. Moreover, we found moderate-quality evidence to suggest that the incidence of neck/shoulder and right upper limb MSDs is not reduced when comparing alternative and conventional mouse with and without arm support. However, given there were multiple comparisons made involving a number of interventions and outcomes, high-quality evidence is needed to determine the effectiveness of these interventions clearly. While we found very-low- to low-quality evidence to suggest that other ergonomic interventions do not prevent work-related MSDs of the upper limb and neck, this was limited by the paucity and heterogeneity of available studies. This review highlights the need for high-quality RCTs examining the prevention of MSDs of the upper limb and neck.

Risk factors for musculoskeletal symptoms of the neck or shoulder alone or neck and shoulder among hospital nurses.

OBJECTIVES: To investigate the relationship between sociodemographic, individual and work place factors, and neck pain alone, shoulder pain alone, and neck and shoulder pain among nurses working across three public hospitals in Melbourne, Australia. METHODS: Information on participant demographics, somatisation tendency, health beliefs, mental and physical health status, workplace physical and psychosocial factors, and musculoskeletal symptoms and pain at several body sites was collected. RESULTS: 1111 participants (response rate 38.6%) were included in the study: 17.2% reported neck pain alone, 11.6% shoulder pain alone and 15.8% both neck and shoulder pain in the past month. Self-reported neck and shoulder pain were independently associated with poorer mental (OR 0.96, 95% CI 0.94 to 0.98) and physical (0.92, 0.90 to 0.95) health and well-being, somatisation (1.77, 1.03 to 3.04) and negative work-causation beliefs (2.51, 1.57 to 3.99). Neck pain alone was more consistently associated with sociodemographic factors, mental (0.97, 0.96 to 0.99) and physical (0.97, 0.94 to 0.99) health and well-being, and shoulder pain alone was associated with physical health and well-being (0.95, 0.92 to 0.98) and fear-avoidance beliefs (0.45, 0.24 to 0.86). CONCLUSION: Risk factors for self-reported pain between regions of the neck and shoulder alone, and neck and shoulder differed. While neck and shoulder pain was consistently associated with several risk factors, neck and shoulder pain in isolation were both associated with physical health and well-being and individually associated with sociodemographic and health beliefs, respectively. These findings suggest that different factors may be associated with a single pain region versus pain in two regions.

Evaluation of the routine use of the anaerobic bottle when using the BACTEC blood culture system.

The established practice of sending blood cultures in an aerobic-anaerobic pair of bottles has been questioned in recent years, and this study was conducted to evaluate the routine use of an anaerobic bottle in the BACTEC blood culture set at the University of Malaya Medical Centre, Kuala Lumpur, from January to December 2004. A total of 11,663 paired blood culture sets were received, of which 3326 were from pediatric patients and 8337 were from adult patients. The overall positive isolation rate was 15%; the positive isolation rate on excluding the anaerobic bottles was 13%. Overall, there were significantly more organisms isolated from the aerobic bottle (p<0.05); however, the best yield was obtained on using the paired aerobic-anaerobic bottles. Among the positive blood culture sets, organisms were isolated from the anaerobic bottle alone in 15.2% of the pediatric sets and in 18.1% of the adult sets. Organisms that grew more frequently in the anaerobic bottle were anaerobes and some facultative anaerobes; however, the difference was not statistically significant except for anaerobes in the adult sets. We recommend that when culturing blood, an aerobic-anaerobic pair of bottles be used rather than an aerobic-aerobic pair, to optimize the recovery of a wider spectrum of organisms, including obligatory anaerobes.