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  • 1.
    Bergman, Joakim
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Klinisk neurovetenskap.
    Svenningsson, A.
    Liv, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa.
    Burman, J.
    Poor correlation between protein levels in different CNS compartments in patients with progressive MS2019Ingår i: Multiple Sclerosis, ISSN 1352-4585, E-ISSN 1477-0970, Vol. 25, s. 432-433Artikel i tidskrift (Övrigt vetenskapligt)
  • 2.
    Jackson, Jennie
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Liv, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Wahlström, Jens
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Occupational risk factors for hospitalization due to cervical disc disorder in a 29-year prospective study of Swedish male construction workers2019Ingår i: PREMUS 2019: 10th International Scientific Conference on the Prevention of Work-Related Musculoskeletal Disorders: From research to evidence based sustainable interventions and practices, 2019, s. 168-168Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Background: The aim of this study was to assess the associations between individual and occupational exposure factors and hospitalization for cervical disc disorder (CDD).

    Methods: CDD was examined prospectively in a cohort of 278 319 Swedish male construction workers who participated in a national health surveillance program (1971-1993). Job title, smoking status, age, height, and weight were recorded on examination. Case data were obtained through linkage with the Swedish national in-patient hospital registry for the period 1987 – 2016; case status was defined by primary diagnosis code M50.0 (ICD-10) or 722.0, 722.4, or 722.7 (ICD-9). A job exposure matrix was developed and occupational exposure estimates were assigned by job title. Self-reported estimates of pain/discomfort from a subset of 87 500 workers were also linked to the database. Poisson regression models were used to estimate the relative risks (RR) for the biomechanical and self-reported factors with adjustment for smoking status, age, BMI and surgical time period.

    Results: There were 562 cases of hospitalization for CDD; the incidence rate was 8.0 cases per 100 000 during the 29-year follow-up period. Smoking status, age, BMI and height were all associated with increased risk (RR 1.21-3.16). Occupational exposure to static work in non-neutral or extreme neck postures, and time spent in awkward postures showed the highest associations with CDD hospitalization (RR = 1.62 – 2.10). Upper arm load and time with arms above shoulders were also associated with increased risk (RR = 1.50 – 1.58). Workers who reported experiencing pain ‘often’ or ‘very often’ during the previous year for any of the neck, shoulder or upper back regions had a 3-fold increase in risk relative to workers reporting no pain.

    Conclusions: Occupational non-neutral neck posture was associated with increased risk of hospitalization for CDD. Our data also suggest an exposure-response relationship for self-reported neck pain/discomfort and risk of hospitalization for CDD.

  • 3.
    Lewis, Charlotte A.
    et al.
    Occupational and Environmental Medicine, Umeå University Hospital, Umeå, Sweden.
    Jackson, Jennie
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Liv, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Wahlström, Jens
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Occupational biomechanical risk factors for surgical treatment of subacromial impingement syndrome (SIS) in a 16-year prospective study among male construction workers2019Ingår i: PREMUS 2019: 10th International Scientific Conference on the Prevention of Work-Related Musculoskeletal Disorders: From research to evidence based sustainable interventions and practices, 2019, s. 165-165Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Background: Shoulder disorders are common in the general population, with an annual prevalence up to over 40% per 1000 person-years. One common disorder is subacromial impingement syndrome (SIS), where a narrowing in the subacromial space causes compression of the tendons or bursa by the surrounding tissues. When conservative treatments are not effective, surgical treatments is often the alternative. The aim of the current study was to assess the association between occupational biomechanical exposures and the occurrence of surgically treated SIS in a large construction worker cohort over a 16-year follow-up period. 

    Methods: A cohort of 280 747 male construction workers who participated in a national occupational health surveillance program (1971-1993) were examined prospectively (1987-2016) for SIS. SIS case status was defined by primary surgical treatment of diagnosis codes M75.1, M75.4, 726B, or 726C (ICD 10 and Swedish ICD 9 code systems), with data from the Swedish national registry for in- and out-patient surgery records. A job exposure matrix (JEM) was developed and biomechanical exposure estimates were assigned according to job title. Poisson regression models adjusted for age, BMI, smoking and a surgical time factor were used to estimate the relative risks (incidence rate ratios) of surgical treatment for SIS for each biomechanical factor.

    Results: There were 1381 cases in the cohort, which corresponded to an incidence rate of surgically treated SIS over the 16-year observation period of 46 cases per 100,000 person years. Increased risk for surgically treated SIS was shown for working with elevated arms (RR=1.27, 95% CI=1.02-1.58), heavy upper arm loads (RR=1.75, 95% CI=1.48-2.08), high grip force (RR=1.64, 95% CI=1.40-1.93), working with hand tools (RR=1.46, 95% CI=1.26-1.70), working with hand tools in a fixed posture (RR=1.28, 95% CI=1.14-1.44), and working with hand-arm vibration (RR=1.30, 95% CI=1.09-1.55).

    Conclusions: Working with elevated arms, high arm load, high grip force and vibrating handheld tools may increase the risk for SIS.

  • 4.
    Liv, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Efficient strategies for collecting posture data using observation and direct measurement2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Relationships between occupational physical exposures and risks of contracting musculoskeletal disorders are still not well understood; exposure-response relationships are scarce in the musculoskeletal epidemiology literature, and many epidemiological studies, including intervention studies, fail to reach conclusive results. Insufficient exposure assessment has been pointed out as a possible explanation for this deficiency. One important aspect of assessing exposure is the selected measurement strategy; this includes issues related to the necessary number of data required to give sufficient information, and to allocation of measurement efforts, both over time and between subjects in order to achieve precise and accurate exposure estimates. These issues have been discussed mainly in the occupational hygiene literature considering chemical exposures, while the corresponding literature on biomechanical exposure is sparse. The overall aim of the present thesis was to increase knowledge on the relationship between data collection design and the resulting precision and accuracy of biomechanical exposure assessments, represented in this thesis by upper arm postures during work, data which have been shown to be relevant to disorder risk.

    Four papers are included in the thesis. In papers I and II, non-parametric bootstrapping was used to investigate the statistical efficiency of different strategies for distributing upper arm elevation measurements between and within working days into different numbers of measurement periods of differing durations. Paper I compared the different measurement strategies with respect to the eventual precision of estimated mean exposure level. The results showed that it was more efficient to use a higher number of shorter measurement periods spread across a working day than to use a smaller number for longer uninterrupted measurement periods, in particular if the total sample covered only a small part of the working day. Paper II evaluated sampling strategies for the purpose of determining posture variance components with respect to the accuracy and precision of the eventual variance component estimators. The paper showed that variance component estimators may be both biased and imprecise when based on sampling from small parts of working days, and that errors were larger with continuous sampling periods. The results suggest that larger posture samples than are conventionally used in ergonomics research and practice may be needed to achieve trustworthy estimates of variance components.

    Papers III and IV focused on method development. Paper III examined procedures for estimating statistical power when testing for a group difference in postures assessed by observation. Power determination was based either on a traditional analytical power analysis or on parametric bootstrapping, both of which accounted for methodological variance introduced by the observers to the exposure data. The study showed that repeated observations of the same video recordings may be an efficient way of increasing the power in an observation-based study, and that observations can be distributed between several observers without loss in power, provided that all observers contribute data to both of the compared groups, and that the statistical analysis model acknowledges observer variability. Paper IV discussed calibration of an inferior exposure assessment method against a superior “golden standard” method, with a particular emphasis on calibration of observed posture data against postures determined by inclinometry. The paper developed equations for bias correction of results obtained using the inferior instrument through calibration, as well as for determining the additional uncertainty of the eventual exposure value introduced through calibration.

    In conclusion, the results of the present thesis emphasize the importance of carefully selecting a measurement strategy on the basis of statistically well informed decisions. It is common in the literature that postural exposure is assessed from one continuous measurement collected over only a small part of a working day. In paper I, this was shown to be highly inefficient compared to spreading out the corresponding sample time across the entire working day, and the inefficiency was also obvious when assessing variance components, as shown in paper II. The thesis also shows how a well thought-out strategy for observation-based exposure assessment can reduce the effects of measurement error, both for random methodological variance (paper III) and systematic observation errors (bias) (paper IV).

  • 5.
    Liv, Per
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Mathiassen, Svend Erik
    Högskolan i Gävle, Centrum för belastningsskadeforskning.
    Heiden, Marina
    Högskolan i Gävle, Centrum för belastningsskadeforskning.
    Wahlström, Jens
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Uncertainties of calibrated exposure estimates, exemplified by working postures assessed by observation and inclinometryManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Objectives: Many occupational exposure variables can be measured using different instruments, of which some can be considered inferior in terms of precision and/or accuracy while others have a superior performance. Thus, working postures can be assessed by observation, which is known to be associated with errors, while direct measurements using inclinometers are assumed to represent a “golden standard”. A possible bias in results obtained by the ”inferior” instrument can be corrected using regression calibration, but the statistical consequences of this procedure are not fully understood. This paper develops procedures for evaluating the precision of an estimate of “true” exposure after calibration, and illustrates them using data from a study of observed upper arm elevation versus corresponding inclinometer measurements.

    Methods: Three random coefficient models for estimating the relationship between inferior (observations) and superior (inclinometer) measurements were constructed, taking methodological (observer) variability into account to different extents. Expressions for estimating the uncertainty of a calibrated exposure (posture) mean value were derived, which identify the specific contributions from sample uncertainty and uncertainty associated with determining the calibration parameters.

    Results: In the example of posture observations, calibration introduced an uncertainty that outweighed the size of the observation bias. Thus, this proved to be an example of calibration not always being appropriate, i.e. in case the trade-off between bias correction and increased uncertainty is unfavorable.

    Conclusions: Calibration of inferior measurements can be a viable tool to correct for bias, but it may add a considerable uncertainty to the eventual mean exposure estimate. Thus, the trade-off between these two calibration effects needs to be considered in each specific case, and further research is needed on the determinants of the trade-off.

  • 6.
    Liv, Per
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Mathiassen, Svend Erik
    Svendsen, Susanne Wulff
    Accuracy and precision of variance components in occupational posture recordings: a simulation study of different data collection strategies2012Ingår i: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 12, s. 58-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Information on exposure variability, expressed as exposure variance components, is of vital use in occupational epidemiology, including informed risk control and efficient study design. While accurate and precise estimates of the variance components are desirable in such cases, very little research has been devoted to understanding the performance of data sampling strategies designed specifically to determine the size and structure of exposure variability. The aim of this study was to investigate the accuracy and precision of estimators of between-subjects, between-days and within-day variance components obtained by sampling strategies differing with respect to number of subjects, total sampling time per subject, number of days per subject and the size of individual sampling periods.

    Methods: Minute-by-minute values of average elevation, percentage time above 90 degrees and percentage time below 15 degrees were calculated in a data set consisting of measurements of right upper arm elevation during four full shifts from each of 23 car mechanics. Based on this parent data, bootstrapping was used to simulate sampling with 80 different combinations of the number of subjects (10, 20), total sampling time per subject (60, 120, 240, 480 minutes), number of days per subject (2, 4), and size of sampling periods (blocks) within days (1, 15, 60, 240 minutes). Accuracy (absence of bias) and precision (prediction intervals) of the variance component estimators were assessed for each simulated sampling strategy.

    Results: Sampling in small blocks within days resulted in essentially unbiased variance components. For a specific total sampling time per subject, and in particular if this time was small, increasing the block size resulted in an increasing bias, primarily of the between-days and the within-days variance components. Prediction intervals were in general wide, and even more so at larger block sizes. Distributing sampling time across more days gave in general more precise variance component estimates, but also reduced accuracy in some cases.

    Conclusions: Variance components estimated from small samples of exposure data within working days may be both inaccurate and imprecise, in particular if sampling is laid out in large consecutive time blocks. In order to estimate variance components with a satisfying accuracy and precision, for instance for arriving at trustworthy power calculations in a planned intervention study, larger samples of data will be required than for estimating an exposure mean value with a corresponding certainty.

  • 7.
    Liv, Per
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Mathiassen, Svend Erik
    Högskolan i Gävle, Centrum för belastningsskadeforskning.
    Svendsen, Susanne Wulff
    Danish Ramazzini Center, Department of Occupational Medicine, Herning Hospital, Denmark.
    Theoretical and empirical efficiency of sampling strategies for estimating upper arm elevation2011Ingår i: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 55, nr 4, s. 436-449Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVES: To investigate the statistical efficiency of strategies for sampling upper arm elevation data, which differed with respect to sample sizes and sample allocations within and across measurement days. The study was also designed to compare standard theoretical predictions of sampling efficiency, which rely on several assumptions about the data structure, with 'true' efficiency as determined by bootstrap simulations.

    METHODS: Sixty-five sampling strategies were investigated using a data set containing minute-by-minute values of average right upper arm elevation, percentage of time with an arm elevated <15°, and percentage of time with an arm elevated >90° in a population of 23 house painters, 23 car mechanics, and 26 machinists, all followed for four full working days. Total sample times per subject between 30 and 240 min were subdivided into continuous time blocks between 1 and 240 min long, allocated to 1 or 4 days per subject. Within day(s), blocks were distributed using either a random or a fixed-interval principle. Sampling efficiency was expressed in terms of the variance of estimated mean exposure values of 20 subjects and assessed using standard theoretical models assuming independence between variables and homoscedasticity. Theoretical performance was compared to empirical efficiencies obtained by a nonparametric bootstrapping procedure.

    RESULTS: We found the assumptions of independence and homoscedasticity in the theoretical model to be violated, most notably expressed through an autocorrelation between measurement units within working days. The empirical variance of the mean exposure estimates decreased, i.e. sampling efficiency increased, for sampling strategies where measurements were distributed widely across time. Thus, the most efficient allocation strategy was to organize a sample into 1-min block collected at fixed time intervals across 4 days. Theoretical estimates of efficiency generally agreed with empirical variances if the sample was allocated into small blocks, while for larger block sizes, the empirical 'true' variance was considerably larger than predicted by theory. Theory overestimated efficiency in particular for strategies with short total sample times per subject.

    CONCLUSIONS: This study demonstrates that when exposure data are autocorrelated within days-which we argue is the major reason why theory overestimates sampling performance-sampling efficiency can be improved by distributing the sample widely across the day or across days, preferably using a fixed-interval strategy. While this guidance is particularly valid when small proportions of working days are assessed, we generally recommend collecting more data than suggested by theory if a certain precision of the resulting exposure estimate is needed. More data per se give a better precision and sampling larger proportion(s) of the working day(s) also alleviate the negative effects of possible autocorrelation in data.

  • 8.
    Liv, Per
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Mathiassen, Svend Erik
    Högskolan i Gävle, Centrum för belastningsskadeforskning.
    Wahlström, Jens
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Statistical power and measurement requirements in studies comparing observed postures between groupsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Ergonomics studies comparing working postures and movements between independent groups are often based on observations. The present paper derives and exemplifies procedures for estimating the statistical power of such studies, addressing the effect of different strategies for allocating observations within and between observers. In the simple case of one observer rating the postures of all subjects in the study one or multiple times, a simple t-test is appropriate for testing the group difference, while statistical models acknowledging rating differences between observers are needed when multiple observers are involved. In the one-observer case, analytical power calculations are feasible, while a parametric bootstrapping approach is suggested and practiced in the paper for the multiple-observers case. Using empirical data from a previous study of postures among hairdressers observed from video recordings (percentages of time with the right upper arm elevated less than 15° and more than 90°), the study demonstrates that a considerable gain in power can be obtained by having one observer doing multiple repeated observations as compared to rating postures only once. Distributing a certain number of video recordings between multiple observers resulted in a loss of power when a simple t-test was used to test the group difference, but the comparison could be accomplished without loss of power if all observers were involved in rating both of the compared groups and the statistical model used to analyze data acknowledged variability in rating between observers. When different observers assessed the two compared groups, power decreased considerably. Thus, the study gives guidance for efficient design of posture observation studies comparing groups, as well as for appropriate statistical procedures for analyzing the data.

  • 9. Magnusson, Peter
    et al.
    Gadler, Fredrik
    Liv, Per
    Mörner, Stellan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Causes of death and mortality in hypertrophic cardiomyopathy patients with implantable defibrillators in Sweden2016Ingår i: Journal of Cardiovascular Medicine, ISSN 1558-2027, E-ISSN 1558-2035, Vol. 17, nr 7, s. 478-484Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    AimsImplantable defibrillators (ICDs) successfully terminate ventricular arrhythmias in hypertrophic cardiomyopathy (HCM), protect against bradycardia, and monitor atrial arrhythmias. This may alter the natural history and causes of death.MethodsThis nationwide observational longitudinal retrospective study of all HCM patients implanted during 1995-2012 obtained data from the Swedish ICD Registry, the National Patient Register, the Cause of Death Register, and were validated by review of medical records.ResultsOf 342 patients (mean age 51.8 years, 70.8% males), 45 died during a total follow-up of 1847 years (mean 5.4 years). Mean age at death was 68.2 years (range 21-83 years; 12 were 75 years). Mean follow-up time among the deceased was 4.9 years (quartiles 1.4-7.4 years). All-cause mortality was higher in HCM patients compared with the age and sex-matched Swedish general population (standardized mortality ratio 3.4; 95% confidence interval 2.4-4.5; P<0.001). Main cause of death was heart failure (n=27), stroke (n=5), cancer (n=3), myocardial infarction (n=2), sepsis (n=2), and others (n=4). Two patients died suddenly, one after the ICD was turned off because of inappropriate shocks, and one patient whose device system was removed after infection. HCM was the main cause of death in 76% of the cases, mainly because of progressive heart failure.ConclusionFor HCM patients, ICDs almost eliminate premature arrhythmic death and result in a shift to heart failure as the cause of death in the majority of cases. Still, mortality in HCM patients remains elevated and management of heart failure and comorbidities must be improved to increase survival.

  • 10. Magnusson, Peter
    et al.
    Gadler, Fredrik
    Liv, Per
    Mörner, Stellan
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Kardiologi.
    Risk Markers and Appropriate Implantable Defibrillator Therapy in Hypertrophic Cardiomyopathy2016Ingår i: Pacing and Clinical Electrophysiology, ISSN 0147-8389, E-ISSN 1540-8159, Vol. 39, nr 3, s. 291-301Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background Risk stratification of sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is mainly based on evaluations from patients at highly specialized centers.

    Aim To evaluate risk markers for appropriate implantable cardioverter defibrillator (ICD) therapy in an unselected, nationwide cohort of HCM. MethodsPatients with an ICD due to HCM were identified from the Swedish ICD Registry since its start in 1995, merged with Patient Register data, and medical records were retrieved. Risk markers for ventricular arrhythmias leading to appropriate ICD therapy were analyzed using Cox proportional hazard ratio (HR).

    Results Of 321 patients (70.1% males), at least one appropriate therapy occurred in 77 (24.0%) during a mean follow-up of 5.4 years (5.3% per year; primary prevention 4.5%, secondary prevention 7.0%). Cumulative incidences at 1 year, 3 years, and 5 years were 8.1%, 15.3%, and 21.3%, respectively. Cardioversion effectively restored rhythm in 52% of the first episode and antitachycardia pacing was sufficient in the remaining. For the whole cohort, ejection fraction (EF) <50% (HR 2.63; P < 0.001) was associated with appropriate ICD therapy. In primary prevention, patients with established risk markers experienced appropriate therapy; atrial fibrillation (AF; HR 2.54; P = 0.010), EF < 50% (HR 2.78; P = 0.004), and nonsustained ventricular tachycardia (HR 1.80; P = 0.109) had the highest HR, and wall thickness 30 mm, syncope, exercise blood pressure response, or family history of SCD had weaker associations.

    Conclusion ICD therapy successfully terminates ventricular arrhythmias in HCM. In addition to conventional risk markers, a history of AF or EF < 50% may be considered in risk stratification.

  • 11. Mathiassen, Svend Erik
    et al.
    Liv, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Wahlström, Jens
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Cost-efficient observation of working postures from video recordings: more videos, more observers or more views per observer?2012Ingår i: Work: A journal of Prevention, Assessment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, Vol. 41, nr Sup. 1, s. 2302-2306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In ergonomics, assessing the working postures of an individual by observation is a very common practice. The present study investigated whether monetary resources devoted to an observational study should preferably be invested in collecting many video recordings of the work, or in having several observers estimate postures from available videos multiple times. On the basis of a data set of observed working postures among hairdressers, necessary information in terms of posture variability, observer variability, and costs for recording and observing videos was entered into equations providing the total cost of data collection and the precision (informative value) of the resulting estimates of two variables: percentages time with the arm elevated <15 degrees and >90 degrees. In all 160 data collection strategies, differing with respect to the number of video recordings and the number of repeated observations of each recording, were simulated and compared for cost and precision. For both posture variables, the most cost-efficient strategy for a given budget was to engage 4 observers to look at available video recordings, rather than to have one observer look at more recordings. Since the latter strategy is the more common in ergonomics practice, we recommend reconsidering standard practice in observational posture assessment.

  • 12.
    Viberg, Andreas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Liv, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa. Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Behndig, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    Lundström, Mats
    Byström, Berit
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Oftalmiatrik.
    The impact of corneal guttata on the results of cataract surgery2019Ingår i: Journal of cataract and refractive surgery, ISSN 0886-3350, E-ISSN 1873-4502, Vol. 45, nr 6, s. 803-809Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose: To study the impact of corneal guttata on postoperative visual acuity and patients' self-assessed visual function after cataract surgery.

    Setting: Patient data from 49 Swedish cataract surgery units.

    Design: Retrospective cross-sectional register-based study.

    Methods: Data from patients who had cataract surgery from 2010 to 2017 and completed the Catquest-9SF questionnaire were obtained from the Swedish National Cataract Register. Logistic proportional odds regression was used to model the impact of corneal guttata on the visual acuity and self-assessed visual function. Adjustments were made for age, sex, ocular comorbidities, days to follow-up, preoperative corrected distance visual acuity (CDVA) and preoperative Rasch person score. The main outcome measures were postoperative CDVA and Rasch person score calculated from the Catquest-9SF questionnaire.

    Results: The study comprised data from 33 741 patients. Cataract surgery greatly improved CDVA and self-assessed visual function in patients both with and without corneal guttata. Still, corneal guttata was significantly associated with a poorer visual acuity and a worse self-assessed visual function after cataract surgery. The negative effect of corneal guttata on visual acuity was most prominent during the first 3 weeks postoperatively, but it persisted at least 3 months postoperatively.

    Conclusions: Patients with corneal guttata benefit substantially from cataract surgery but have an additional risk for inferior results compared with patients without corneal guttata. These findings could serve as valuable tools in clinical practice, in particular, when deciding to perform cataract surgery and how to inform the patient about surgical benefits and risks.

  • 13.
    Wahlström, Jens
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Liv, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Jackson, Jennie
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för hållbar hälsa.
    Occupational risk factors for surgically treated carpal tunnel syndrome: a prospective cohort study of 220,610 Swedish construction workers2019Ingår i: PREMUS 2019: 10th International Scientific Conference on the Prevention of Work-Related Musculoskeletal Disorders: From research to evidence based sustainable interventions and practices, 2019, s. 141-141Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Background: Carpal tunnel syndrome (CTS) is the most common upper extremity nerve entrapment syndrome . The aim of this study was to determine the association between occupational biomechanical exposures and occurrence of surgically treated CTS in construction workers over a 16-year follow-up.

    Methods: A cohort of 220 610 male construction workers who participated in a national occupational health surveillance program (1971–1992) were examined prospectively (2001–2016) for surgically treated CTS. Cases were determined via a linkage with the Swedish Hospital Outpatient Register. Job title (construction trade), smoking status, height, weight and age were recorded on examination. Job titles were merged into occupational groups of workers performing similar work tasks and having similar training. Occupational biomechanical exposure estimates were assigned to each occupational group using a job exposure matrix (JEM) developed for the study. Poisson regression models were used to assess the relative risks for each biomechanical exposure. Relative risks were adjusted for age, surgical time period, BMI, and smoking status at first examination.

    Results: There were 4048 cases of surgically treated CTS within the cohort which represented an incidence rate of 134 cases per 100 000 person years. Workers exposed to medium and high forceful handgrip factors had relative risks of 1.3 (95% CI 1.16-1.38) and 1.6 (95% CI 1.50-1.77), respectively, of undergoing surgical treatment for CTS compared to low exposed workers. Workers exposed to medium and high exposure to hand-arm vibration had relative risks of 1.3 (95% CI 1.19-1.34) and 1.2 (95% CI 1.07-1.28), respectively, of undergoing surgical treatment for CTS compared to low exposed workers.

    Conclusions: In conclusion, forceful hand-grip work and exposure to hand-arm vibration increased the risk for surgically treated carpal tunnel syndrome.

  • 14.
    Wahlström, Jens
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Mathiassen, Svend Erik
    Liv, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Hedlund, Pernilla
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Ahlgren, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Sjukgymnastik.
    Forsman, Mikael
    Upper arm postures and movements in female hairdressers across four full working days2010Ingår i: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 54, nr 5, s. 584-594Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    OBJECTIVES: To describe upper arm postures and movements among female hairdressers, including the variability between hairdressers, between days within hairdresser, and between tasks, as a basis for understanding the characteristics of exposures in the job, considering possible sources of variation and recovery, and discussing appropriate exposure assessment strategies.

    METHODS: Data on upper arm postures were collected using inclinometers during four working days the same week from 28 female hairdressers working in 13 salons. Twenty of the hairdressers noted customer on and off times in a diary, to allow separate analyses of customer tasks (CT) and auxiliary non-customer tasks (AT), including breaks. For a number of posture and movement variables, mean values and variance components between subjects (BS) and within subjects between days (BD) were estimated using restricted maximum likelihood algorithms in one-way random effect models.

    RESULTS: For the 20 hairdressers with diaries, CT accounted for 279 min (58%) (SD(BS) = 39 min and SD(BD) = 85 min) of the working day and AT and breaks for 207 min (42%) (SD(BS) = 46 min and SD(BD) = 88 min). The hairdressers worked with the right arm elevated >60 degrees for 6.8% of the whole job (SD(BS) = 2.8% and SD(BD) = 2.0%). On average, the hairdressers worked with the right arm elevated >60 degrees for 9.0% of the time during CT, compared to 3.7% during AT, resulting in a contrast between tasks of 0.35.

    CONCLUSIONS: Hairdressers may be at risk for developing musculoskeletal disorders in the neck and shoulders due to a considerable occurrence of highly elevated arms, especially during CT. On the other hand, we do not find reasons to classify hairdressing as a job with too little variation. Posture variability between days within hairdressers was in the same order of magnitude as that between hairdressers, suggesting that 'typical' workdays do not exist. The exposure contrast between CT and AT for variables describing elevated arm postures indicates that for these variables a simple task-based approach for estimating job exposure could be successful.

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