Study on Evolution of Micropipes from Hexagonal Voids in 4H-SiC Crystals by Cathodoluminescence Imaging.

This paper presents an investigation on micropipe evolution from hexagonal voids in physical vapor transport-grown 4H-SiC single crystals using the cathodoluminescence (CL) imaging technique. Complementary techniques optical microscopy, scanning electron microscopy, and energy-dispersive spectroscopy (EDS) are also used to understand the formation mechanism of hexagonal voids along with the origin of pipes from these voids. The ability of CL to image variations along the depth of the sample provides new insights on how micropipes are attached to hexagonal voids that lie deep within the bulk single crystals. CL imaging confirms that multiple micropipes can originate from a single hexagonal void. EDS mapping shows that the inside of the micropipe walls exhibits higher levels of carbon. Investigation of the seed region by optical imaging shows that improper fixing of the seed to the crucible lid is the root cause for the formation of hexagonal voids that subsequently lead to micropipe formation.

Outpatient ADE (cytarabine, daunorubicin, and etoposide) is feasible and effective for the first relapse of pediatric acute myeloid leukemia: A prospective, phase II study.

BACKGROUND: Approximately 40% children with acute myeloid leukemia (AML) invariably relapse, after attaining the first complete remission (CR), with dismal long-term outcome. There is little consensus regarding choice of optimal induction chemotherapy regimen for relapsed pediatric AML. PROCEDURE: A prospective single arm phase II study (CTRI/2017/02/007757) was carried out at our center to evaluate the safety and efficacy of outpatient cytarabine, daunorubicin, and etoposide (ADE) regimen in pediatric AML (≤18 years) at the first relapse. Response evaluation was done by bone marrow aspiration morphology along with minimal residual disease (MRD) assessment. All adverse events including need and duration of hospitalization, transfusion support, and antimicrobial use were recorded. RESULTS: Total 45 patients were included with median age of 12 years. The CR rate of the cohort was 66% and 54% of patients were MRD negative. The estimated 2-year event-free survival (EFS) and overall survival (OS) were 29% (±7%) and 34% (±7%), respectively. The presence of fever at relapse was associated with inferior CR rate (P = .001), positive MRD (P = .01), and inferior EFS (P = .02), while not achieving nadir absolute neutrophil count of zero during induction was associated with inferior CR rate (P = .03) and inferior OS (P = .04). Approximately all patients developed ≥Grade 3 cytopenia and febrile neutropenia. Twenty-six (59%) patients required hospitalization for management of toxicity and there were four (9%) deaths attributed to infection. CONCLUSION: ADE is an effective induction regimen for pediatric AML patients at the first relapse with reasonable toxicity profile. Outpatient administration of the regimen is feasible in the presence of proper support structure and rigorous follow up.

Changes in Mandibular Third Molar Angulation in High-anchorage Extraction vs Non-extraction Orthodontic Treatment: A Prospective Study.

AIM AND OBJECTIVE: The study aimed to compare the prospective changes in mandibular third molar angulation in high anchorage cases treated with first premolar extractions vs non-extraction orthodontic treatment. MATERIALS AND METHODS: The sample consisted of 56 nongrowing patients: Group I had 26 patients with a high anchorage requirement who underwent first premolar extractions and group II had 30 patients who underwent non-extraction treatment. Pretreatment, mid-treatment, and posttreatment panoramic radiographs were obtained for group I and pretreatment and posttreatment for group II. Angle between M2 (second molar)-horizontal reference plane (HRP), M3 (third molar)-HRP, and M2-M3 were measured bilaterally. Data were analyzed using Student t test and ANOVA test (p value < 0.05). RESULTS: Statistically significant increase was found between the pretreatment, mid-treatment, and posttreatment values of M2-M3 in group I (p value = 0.02 R and p value = 0.049 L) and between pretreatment to posttreatment values of M2-HRP in group II bilaterally (p value = 0.001). Significant increase was found in the M2-M3 angulations in group II on the right side (p value = 0.036). M3-HRP decreased in group I without reaching statistical significance. No statistically significant intergroup differences were found between the two groups in relation to M2-HRP, M3-HRP, and M2-M3 angulations. CONCLUSION: M2-M3 angulations increased significantly bilaterally in group I and on the right side in group II, indicating worsening of third molar angulation. M3-HRP worsened in group I without reaching statistical significance. Extraction therapy in high anchorage cases does not lead to an improvement in third molar angulation. CLINICAL SIGNIFICANCE: The extraction of first premolars in high anchorage cases does not lead to an improvement in the angulation of mandibular third molars; moreover, the angulation worsened with extraction therapy. Prospective orthodontic patients need to be cautioned against any improvement in mesioangular impaction of mandibular third molars in high anchorage premolar extraction cases.

Pathophysiological Mechanisms and Neurological Manifestations in COVID-19.

With increasing knowledge of the coronavirus disease-2019 (COVID-19), we now understand that COVID-19 presents with various extrapulmonary manifestations with multi-organ involvement. Involvement of the central nervous system (CNS) occurs probably via transsynaptic spread or transfer across the blood-brain barrier. Hypoxia, immune-mediated injury, and vascular damage are the potential mechanisms for the CNS manifestations. Headache, dizziness, chemosensory disturbances, such as loss of smell, taste, encephalopathy, stroke, etc., are among the commonly encountered neurological presentations. Headache is identified as one of the red flag symptoms for COVID-19. Sudden onset of loss of smell and/or taste in the absence of nasal congestion can help in COVID-19 case identification and testing prioritization. Both hemorrhagic and ischemic brain injury is common in patients developing stroke. Besides these, COVID-19-associated CNS involvement demands more careful attention toward patients with existing neurological disorders especially that are managed with immunosuppressant agents. In all, neurological involvement in COVID-19 is not uncommon and may precede, occur concomitantly or after the respiratory involvement. It may also be the sole presentation in some of the patients necessitating high vigilance for COVID-19. In this review, we briefly discussed the pathogenesis of CNS involvement and some important neurological manifestations in COVID-19. How to cite this article: Zirpe KG, Dixit S, Kulkarni AP, Sapra H, Kakkar G, Gupta R, et al. Pathophysiological Mechanisms and Neurological Manifestations in COVID-19. Indian J Crit Care Med 2020;24(10):975-980.

Incident CTS in a large pooled cohort study: associations obtained by a Job Exposure Matrix versus associations obtained from observed exposures.

BACKGROUND: There is growing use of a job exposure matrix (JEM) to provide exposure estimates in studies of work-related musculoskeletal disorders; few studies have examined the validity of such estimates, nor did compare associations obtained with a JEM with those obtained using other exposures. OBJECTIVE: This study estimated upper extremity exposures using a JEM derived from a publicly available data set (Occupational Network, O*NET), and compared exposure-disease associations for incident carpal tunnel syndrome (CTS) with those obtained using observed physical exposure measures in a large prospective study. METHODS: 2393 workers from several industries were followed for up to 2.8 years (5.5 person-years). Standard Occupational Classification (SOC) codes were assigned to the job at enrolment. SOC codes linked to physical exposures for forceful hand exertion and repetitive activities were extracted from O*NET. We used multivariable Cox proportional hazards regression models to describe exposure-disease associations for incident CTS for individually observed physical exposures and JEM exposures from O*NET. RESULTS: Both exposure methods found associations between incident CTS and exposures of force and repetition, with evidence of dose-response. Observed associations were similar across the two methods, with somewhat wider CIs for HRs calculated using the JEM method. CONCLUSION: Exposures estimated using a JEM provided similar exposure-disease associations for CTS when compared with associations obtained using the 'gold standard' method of individual observation. While JEMs have a number of limitations, in some studies they can provide useful exposure estimates in the absence of individual-level observed exposures.

South Asian Cardiovascular Disease & Cancer Risk: Genetics & Pathophysiology.

South Asians (SAs) are at heightened risk for cardiovascular disease as compared to other ethnic groups, facing premature and more severe coronary artery disease, and decreased insulin sensitivity. This disease burden can only be partially explained by conventional risk factors, suggesting the need for a specific cardiovascular risk profile for SAs. Current research, as explored through a comprehensive literature review, suggests the existence of population specific genetic risk factors such as lipoprotein(a), as well as population specific gene modulating factors. This review catalogues the available research on cardiovascular disease and genetics, anthropometry, and pathophysiology, and cancer genetics among SAs, with a geographical focus on the U.S. A tailored risk profile will hinge upon population customized classification and treatment guidelines, informed by continued research.

Risk assessments using the Strain Index and the TLV for HAL, Part II: Multi-task jobs and prevalence of CTS.

The Strain Index (SI) and the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value for hand activity level (TLV for HAL) have been shown to be associated with prevalence of distal upper-limb musculoskeletal disorders such as carpal tunnel syndrome (CTS). The SI and TLV for HAL disagree on more than half of task exposure classifications. Similarly, time-weighted average (TWA), peak, and typical exposure techniques used to quantity physical exposure from multi-task jobs have shown between-technique agreement ranging from 61% to 93%, depending upon whether the SI or TLV for HAL model was used. This study compared exposure-response relationships between each model-technique combination and prevalence of CTS. Physical exposure data from 1,834 workers (710 with multi-task jobs) were analyzed using the SI and TLV for HAL and the TWA, typical, and peak multi-task job exposure techniques. Additionally, exposure classifications from the SI and TLV for HAL were combined into a single measure and evaluated. Prevalent CTS cases were identified using symptoms and nerve-conduction studies. Mixed effects logistic regression was used to quantify exposure-response relationships between categorized (i.e., low, medium, and high) physical exposure and CTS prevalence for all model-technique combinations, and for multi-task workers, mono-task workers, and all workers combined. Except for TWA TLV for HAL, all model-technique combinations showed monotonic increases in risk of CTS with increased physical exposure. The combined-models approach showed stronger association than the SI or TLV for HAL for multi-task workers. Despite differences in exposure classifications, nearly all model-technique combinations showed exposure-response relationships with prevalence of CTS for the combined sample of mono-task and multi-task workers. Both the TLV for HAL and the SI, with the TWA or typical techniques, appear useful for epidemiological studies and surveillance. However, the utility of TWA, typical, and peak techniques for job design and intervention is dubious.

Association between wrist ratio and carpal tunnel syndrome: Effect modification by body mass index.

INTRODUCTION: Previous studies have reported higher wrist ratios (WR) related to carpal tunnel syndrome (CTS) but have not assessed effect modification by obesity and may have inadequately controlled for confounders. METHODS: Baseline data of a multicenter prospective cohort study were analyzed. CTS was defined by nerve conduction study (NCS) criteria and symptoms. RESULTS: Among the 1,206 participants, a square-shaped wrist was associated with CTS after controlling for confounders (prevalence ratio = 2.27; 95% confidence interval [95% CI], 1.33-3.86). Body mass index (BMI) was a strong effect modifier on the relationship between WR and both CTS and abnormal NCS results, with normal weight strata of rectangular versus square wrists = 8.18 (95% CI, 1.63-49.96) and 7.12 (95% CI, 2.19-23.16), respectively. DISCUSSION: A square wrist is significantly associated with CTS after controlling for confounders. Effect modification by high BMI masked the eightfold magnitude adjusted relationship seen between WR and CTS among normal weight participants. Muscle Nerve 56: 1047-1053, 2017.

Association between Epicondylitis and Cardiovascular Risk Factors in Pooled Occupational Cohorts.

BACKGROUND: The pathophysiology of lateral epicondylitis (LE) is unclear. Recent evidence suggests some common musculoskeletal disorders may have a basis in cardiovascular disease (CVD) risk factors. Thus, we examined CVD risks as potential LE risks. METHODS: Workers (n = 1824) were enrolled in two large prospective studies and underwent structured interviews and physical examinations at baseline. Analysis of pooled baseline data assessed the relationships separately between a modified Framingham Heart Study CVD risk score and three prevalence outcomes of: 1) lateral elbow pain, 2) positive resisted wrist or middle finger extension, and 3) a combination of both symptoms and at least one resisted maneuver. Quantified job exposures, personal and psychosocial confounders were statistically controlled. Odds ratios (ORs) and 95% Confidence Intervals (CIs) were calculated. RESULTS: There was a strong relationship between CVD risk score and lateral elbow symptoms, resisted wrist or middle finger extension and LE after adjustment for confounders. The adjusted ORs for symptoms were as high as 3.81 (95% CI 2.11, 6.85), for positive examination with adjusted odds ratios as high as 2.85 (95% CI 1.59, 5.12) and for combined symptoms and physical examination 6.20 (95% CI 2.04, 18.82). Relationships trended higher with higher CVD risk scores. CONCLUSIONS: These data suggest a potentially modifiable disease mechanism for LE.

Sit-To-Stand Lift: Effects of Lifted Height on Weight Borne and Upper Extremity Strength Requirements.

To prevent back and shoulder injuries to nursing personnel, sit-to-stand lifts are used to transfer partial-weight-bearing patients with upper extremity strength. However, the weight-bearing capacity and upper extremity strength required of patients have not been defined. The objectives of this study were to determine: (a) the percentage of body weight borne by the patient when lifted to different heights in the lift and (b) whether a patient needs upper extremity strength. Nineteen healthy normal-weight volunteers (ages 19-39) were transferred from a hospital bed to a wheelchair using (a) a gait belt and (b) a sit-to-stand lift. With legs secured in the lift, participants were lifted to five different heights (knee angles 120-180 degrees) while holding and not holding the lift handles. Participants supported a greater percentage of body weight as they were lifted higher, increasing from 60% to almost 100% (p < .01). Holding the handles did not have an effect on weight borne overall. At low heights, slightly less weight was borne when not using the handles than with them, and no difference in weight borne was found at heights near standing (p < .01). All participants felt more comfortable and safer transferring from bed to wheelchair with the mechanical lift than with the gait belt (p < .01). Results are limited to normal-weight patients but suggest that sit-stand lifts can be used in patients without upper extremity strength. Patients with limited weight-bearing capacity can be transferred by not raising them high in the lift. © 2016 Wiley Periodicals, Inc.

Risk assessments using the Strain Index and the TLV for HAL, Part I: Task and multi-task job exposure classifications.

BACKGROUND: The Strain Index (SI) and the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value for Hand Activity Level (TLV for HAL) use different constituent variables to quantify task physical exposures. Similarly, time-weighted-average (TWA), Peak, and Typical exposure techniques to quantify physical exposure from multi-task jobs make different assumptions about each task's contribution to the whole job exposure. Thus, task and job physical exposure classifications differ depending upon which model and technique are used for quantification. This study examines exposure classification agreement, disagreement, correlation, and magnitude of classification differences between these models and techniques. METHODS: Data from 710 multi-task job workers performing 3,647 tasks were analyzed using the SI and TLV for HAL models, as well as with the TWA, Typical and Peak job exposure techniques. Physical exposures were classified as low, medium, and high using each model's recommended, or a priori limits. Exposure classification agreement and disagreement between models (SI, TLV for HAL) and between job exposure techniques (TWA, Typical, Peak) were described and analyzed. RESULTS: Regardless of technique, the SI classified more tasks as high exposure than the TLV for HAL, and the TLV for HAL classified more tasks as low exposure. The models agreed on 48.5% of task classifications (kappa = 0.28) with 15.5% of disagreement between low and high exposure categories. Between-technique (i.e., TWA, Typical, Peak) agreement ranged from 61-93% (kappa: 0.16-0.92) depending on whether the SI or TLV for HAL was used. CONCLUSIONS: There was disagreement between the SI and TLV for HAL and between the TWA, Typical and Peak techniques. Disagreement creates uncertainty for job design, job analysis, risk assessments, and developing interventions. Task exposure classifications from the SI and TLV for HAL might complement each other. However, TWA, Typical, and Peak job exposure techniques all have limitations. Part II of this article examines whether the observed differences between these models and techniques produce different exposure-response relationships for predicting prevalence of carpal tunnel syndrome.

The Composite Strain Index (COSI) and Cumulative Strain Index (CUSI): methodologies for quantifying biomechanical stressors for complex tasks and job rotation using the Revised Strain Index.

The Composite Strain Index (COSI) quantifies biomechanical stressors for complex tasks consisting of exertions at different force levels and/or with different exertion times. The Cumulative Strain Index (CUSI) further integrates biomechanical stressors from different tasks to quantify exposure for the entire work shift. The paper provides methodologies to compute COSI and CUSI along with examples. Complex task simulation produced 169,214 distinct tasks. Use of average, time-weighted average (TWA) and peak force and COSI classified 66.9, 28.2, 100 and 38.9% of tasks as hazardous, respectively. For job rotation the simulation produced 10,920 distinct jobs. TWA COSI, peak task COSI and CUSI classified 36.5, 78.1 and 66.6% jobs as hazardous, respectively. The results suggest that the TWA approach systematically underestimates the biomechanical stressors and peak approach overestimates biomechanical stressors, both at the task and job level. It is believed that the COSI and CUSI partially address these underestimations and overestimations of biomechanical stressors. Practitioner Summary: COSI quantifies exposure when applied hand force and/or duration of that force changes during a task cycle. CUSI integrates physical exposures from job rotation. These should be valuable tools for designing and analysing tasks and job rotation to determine risk of musculoskeletal injuries.

The Revised Strain Index: an improved upper extremity exposure assessment model.

The Revised Strain Index (RSI) is a distal upper extremity (DUE) physical exposure assessment model based on: intensity of exertion, frequency of exertion, duration per exertion, hand/wrist posture and duration of task per day. The RSI improves upon the 1995 Strain Index (SI) by using continuous rather than categorical multipliers, and replacing duty cycle with duration per exertion. In a simulation of 13,944 tasks, the RSI and 1995 SI showed good agreement in risk predictions for 1995 SI scores ≤3 (safe) and >13.5 (hazardous). For tasks with 1995 SI scores of >3 and ≤13.5, the two models showed marked disagreement, with the RSI providing much greater discriminations between 'safe' and 'hazardous' tasks for various combinations of force, repetition and duty cycle. We believe the RSI is a substantially improved model that will be useful for DUE task analysis, intervention and design. Practitioner Summary: RSI is a substantial improvement over the 1995 SI. It should be a valuable tool for designing and analysing tasks to determine risk of musculoskeletal injuries. RSI is applicable to a wide variety of tasks including very low force and very high repetition tasks such as keyboard use.

Biomechanical and psychosocial exposures are independent risk factors for carpal tunnel syndrome: assessment of confounding using causal diagrams.

BACKGROUND: Between 2001 and 2010, six research groups conducted coordinated prospective studies of carpal tunnel syndrome (CTS) incidence among US workers from various industries to estimate exposure-response relationships. OBJECTIVE: This analysis examined the presence and magnitude of confounding between biomechanical and workplace psychosocial factors and incidence of dominant-hand CTS. METHODS: 1605 participants, without CTS at enrolment, were followed for up to 3.5 years (2471 person-years). Demographic information, medical history and workplace psychosocial stress measures were collected at baseline. Individual workplace biomechanical exposures were collected for each task and combined across the workweek using time-weighted averaging (TWA). CTS case criteria were based on symptoms and results of electrophysiological testing. HRs were estimated with Cox proportional hazard models. Confounding was assessed using causal diagrams and an empirical criterion of 10% or greater change in effect estimate magnitude. RESULTS: There were 109 incident CTS cases (IR=4.41/100 person-years; 6.7% cumulative incidence). The relationships between CTS and forceful repetition rate, % time forceful hand exertion and the Threshold Limit Value for Hand Activity Level (TLV-HAL) were slightly confounded by decision latitude with effect estimates being attenuated towards the null (10-14% change) after adjustment. The risk of CTS among participants reporting high job strain was attenuated towards the null by 14% after adjusting for the HAL Scale or the % time forceful hand exertions. CONCLUSIONS: Although attenuation of the relationships between CTS and some biomechanical and work psychosocial exposures was observed after adjusting for confounding, the magnitudes were small and confirmed biomechanical and work psychosocial exposures as independent risk factors for incident CTS.

The Cumulative Lifting Index (CULI) for the Revised NIOSH Lifting Equation: Quantifying Risk for Workers With Job Rotation.

OBJECTIVE: The objectives were to: (a) develop a continuous frequency multiplier (FM) for the Revised NIOSH Lifting Equation (RNLE) as a function of lifting frequency and duration of a lifting task, and (b) describe the Cumulative Lifting Index (CULI), a methodology for estimating physical exposure to workers with job rotation. BACKGROUND: The existing FM for the RNLE (FME) does not differentiate between task duration >2 hr and <8 hr, which makes quantifying physical exposure to workers with job rotation difficult and presents challenges to job designers. METHOD: Using the existing FMs for 1, 2, and 8 hr of task durations, we developed a continuous FM (FMP) that extends to 12 hr per day. We simulated 157,500 jobs consisting of two tasks each and, using different combinations of Frequency Independent Lifting Index, lifting frequency and duration of lifting. Biomechanical stresses were estimated using the CULI, time-weighted average (TWA), and peak exposure. RESULTS: The median difference between FME and FMP was ±1% (range: 0%-15%). Compared to CULI, TWA underestimated risk of low-back pain (LBP) for 18% to 30% of jobs, and peak exposure for an assumed 8-hr work shift overestimated risk of LBP for 20% to 25% of jobs. Peak task exposure showed 90% agreement with CULI but ignored one of two tasks. CONCLUSION: The CULI partially addressed the underestimation of physical exposure using the TWA approach and overestimation of exposure using the peak-exposure approach. APPLICATION: The proposed FM and CULI may provide more accurate physical exposure estimates, and therefore estimated risk of LBP, for workers with job rotation.

Evaluation of the Impact of the Revised National Institute for Occupational Safety and Health Lifting Equation.

OBJECTIVE: The objective of this article is to evaluate the impact of the Revised National Institute for Occupational Safety and Health Lifting Equation (RNLE). BACKGROUND: The RNLE has been used extensively as a risk assessment method for prevention of low back pain (LBP). However, the impact of the RNLE has not been documented. METHODS: A systematic review of the literature on the RNLE was conducted. The review consisted of three parts: characterization of the RNLE publications, assessment of the impact of the RNLE, and evaluation of the influences of the RNLE on ergonomic standards. The literature for assessing the impact was categorized into four research areas: methodology, laboratory, field, and risk assessment studies using the Lifting Index (LI) or Composite LI (CLI), both of which are the products of the RNLE. RESULTS: The impact of the RNLE has been both widespread and influential. We found 24 studies that examined the criteria used to define lifting capacity used by the RNLE, 28 studies that compared risk assessment methods for identifying LBP, 23 studies that found the RNLE useful in identifying the risk of LBP with different work populations, and 13 studies on the relationship between LI/CLI and LBP outcomes. We also found evidence on the adoption of the RNLE as an ergonomic standard for use by various local, state, and international entities. CONCLUSION: The review found 13 studies that link LI/CLI to adverse LBP outcomes. These studies showed a positive relationship between LI/CLI metrics and the severity of LBP outcomes.

Effect of Capparis spinosa Linn. extract on lipopolysaccharide-induced cognitive impairment in rats.

Cognitive disorders in mankind are not uncommon. Apart from neurodegenerative diseases such as Alzheimer's (AD), various stresses also affect cognitive functions. Plants are known to be potential source of compounds that ameliorate several diseases including cognitive impairment. Here, we evaluated effect of aqueous extract of caper (Capparis spinosa) buds on lipopolysaccharide-induced cognitive impairment in rats using two different oral doses i.e. 10 (pre-treatment) and 30 mg/rat(post-treatment) through assessment of behavioural (Morris Water maze test and Y maze test), biochemical (Cholinesterase assay) and histopathological (H&E staining) parameters. Lipopolysaccharide (from E. coli) administration resulted in an increased neurodegeneration and time taken to reach the platform (in Morris water maze). The increased neurodegeneration in CA1 region of hippocampus was significantly reduced in animals which received caper bud extract; they showed marked reduction in time taken to reach the platform at both the dose levels. The experiment demonstrated that caper bud extract exhibits potential protective effect against learning and memory damage induced by chronic administration of lipopolysaccharide (175 µg/kg) for 7 days. The results suggest that the caper bud extract could be explored for its use in the treatment of cognitive disorders.

Relationships between job organisational factors, biomechanical and psychosocial exposures.

The relationships between work organisational, biomechanical and psychosocial factors were studied using cross-sectional data from a pooled dataset of 1834 participants. The work organisational factors included: job rotation, overtime work, having second jobs and work pace. Task and job level biomechanical variables were obtained through sub-task data collected in the field or analysed in the laboratory. Psychosocial variables were collected based on responses to 10 questions. The results showed that job rotations had significant effects on all biomechanical and most psychosocial measures. Those with job rotations generally had higher job biomechanical stressors, and lower job satisfaction. Overtime work was associated with higher job biomechanical stressors, and possibly self-reported physical exhaustion. Those having second jobs reported getting along with co-workers well. Work pace had significant influences on all biomechanical stressors, but its impact on job biomechanical stressors and psychosocial effects are complicated. PRACTITIONER SUMMARY: The findings are based on a large number of subjects collected by three research teams in diverse US workplaces. Job rotation practices used in many workplaces may not be effective in reducing job biomechanical stressors for work-related musculoskeletal disorders. Overtime work is also associated with higher biomechanical stressors.

General population job exposure matrix applied to a pooled study of prevalent carpal tunnel syndrome.

A job exposure matrix may be useful for the study of biomechanical workplace risk factors when individual-level exposure data are unavailable. We used job title-based exposure data from a public data source to construct a job exposure matrix and test exposure-response relationships with prevalent carpal tunnel syndrome (CTS). Exposures of repetitive motion and force from the Occupational Information Network were assigned to 3,452 active workers from several industries, enrolled between 2001 and 2008 from 6 studies. Repetitive motion and force exposures were combined into high/high, high/low, and low/low exposure groupings in each of 4 multivariable logistic regression models, adjusted for personal factors. Although force measures alone were not independent predictors of CTS in these data, strong associations between combined physical exposures of force and repetition and CTS were observed in all models. Consistent with previous literature, this report shows that workers with high force/high repetition jobs had the highest prevalence of CTS (odds ratio = 2.14-2.95) followed by intermediate values (odds ratio = 1.09-2.27) in mixed exposed jobs relative to the lowest exposed workers. This study supports the use of a general population job exposure matrix to estimate workplace physical exposures in epidemiologic studies of musculoskeletal disorders when measures of individual exposures are unavailable.

Biomechanical risk factors for carpal tunnel syndrome: a pooled study of 2474 workers.

BACKGROUND: Between 2001 and 2010, five research groups conducted coordinated prospective studies of carpal tunnel syndrome (CTS) incidence among US workers from various industries and collected detailed subject-level exposure information with follow-up of symptoms, electrophysiological measures and job changes. OBJECTIVE: This analysis examined the associations between workplace biomechanical factors and incidence of dominant-hand CTS, adjusting for personal risk factors. METHODS: 2474 participants, without CTS or possible polyneuropathy at enrolment, were followed up to 6.5 years (5102 person-years). Individual workplace exposure measures of the dominant hand were collected for each task and included force, repetition, duty cycle and posture. Task exposures were combined across the workweek using time-weighted averaging to estimate job-level exposures. CTS case-criteria were based on symptoms and results of electrophysiological testing. HRs were estimated using Cox proportional hazard models. RESULTS: After adjustment for covariates, analyst (HR=2.17; 95% CI 1.38 to 3.43) and worker (HR=2.08; 95% CI 1.31 to 3.39) estimated peak hand force, forceful repetition rate (HR=1.84; 95% CI 1.19 to 2.86) and per cent time spent (eg, duty cycle) in forceful hand exertions (HR=2.05; 95% CI 1.34 to 3.15) were associated with increased risk of incident CTS. Associations were not observed between total hand repetition rate, per cent duration of all hand exertions, or wrist posture and incident CTS. CONCLUSIONS: In this prospective multicentre study of production and service workers, measures of exposure to forceful hand exertion were associated with incident CTS after controlling for important covariates. These findings may influence the design of workplace safety programmes for preventing work-related CTS.