Validity of self-reports of knee-straining activities at work: a field study with 6-month follow-up

Abstract

ObjectivesTo measure short-term and long-term validity of self-reported duration of kneeling and squatting at work and to examine the possibility of differential misclassification due to knee complaints.MethodsWork-related kneeling and squatting were analysed for 190 male subjects (mean age, 35.0 and SD, 11.5) in field by both measurements and questionnaires. Posture capturing was performed with an ambulatory measuring system (CUELA). Immediately after the measurement (t0), each participant was asked to estimate frequency and duration of five specific knee postures taken during the measurement period. After 6 months (t1), the survey was repeated (n = 125). Health status of all subjects was recorded by Nordic questionnaire. Statistical analysis was performed by using nonparametric tests, correlations, and Bland–Altman plots.ResultsAt both time points, subjects were able to recall the occurrence of knee postures rather well (100.0–57.6 % agreement) but many of them failed in quantifying their knee load. We found poor-to-moderate correlations between measurements and self-reports for all examined postures in both surveys (0.23 < ρ < 0.63). The durations of knee postures were both over- and underestimated but overestimations predominated (t0, 74.7 % and t1, 87.2 % overestimations). High-exposed subjects seemed to misjudge their exposure to a greater extent than low-exposed ones, while knee complaints seemed to have no impact on the assessment behaviour.ConclusionsAs our study showed, self-reported knee loading may deviate widely from measured exposure. These limitations of self-reporting emphasise the arguments in favour of using objective data whenever possible, for example by complementing self-reported occurrence of knee postures with quantitative measurement data.Electronic supplementary materialThe online version of this article (doi:10.1007/s00420-012-0758-4) contains supplementary material, which is available to authorized users.

Occupational kneeling and squatting: development and validation of an assessment method combining measurements and diaries

“…But irrespective of the strategy selected, valid exposure data are still required. A parallel conducted comparison of our measuring data and workers’ self-reports (Ditchen et al 2013) showed that subjects were not able to assess their time spent in knee-straining postures reliably, both immediately after the measurement and six months later. But on the other hand, workers were able to accurately remember the occurrence of different knee-straining postures while performing a specific task.…”

“…The results show that 75 % of occupational exposure to the knee was in the posture of kneeling and less than 25 % in sitting on heels, squatting, and crawling. This might be an important hint for the interpretation of self-reported exposure to the knee where subjects often fail to assess the duration they spent in different knee postures correctly (Ditchen et al 2013). Despite this predominance of one posture, our findings illustrate huge variety of occupational exposure to the knee and the difficulty of quantifying this exposure by specific categories, for example job categories.…”

“…In studies examining dose–response relationships between knee-straining work activities and degenerative knee disorders, retrospective exposure assessment has usually been based on self-reports (Felson et al 1991; Vingard et al 1991; Coggon et al 2000; Sandmark et al 2000; Seidler et al 2008; Muraki et al 2009; Klussmann et al 2010). However, as various studies have shown, the validity of self-reports, specifically in this field, might be questionable (Baty et al 1986; Burdorf and Laan 1991; Viikari-Juntura et al 1996; Ditchen et al 2013). …”

Applications of the Standardized Nordic Questionnaire: A Review

“…Bruusgaard et al (2012) [276] Norway Application of the NMQ in a population group. Ditchen et al (2013) [277] Germany Application of the NMQ in a varied occupational group. Nordander et al (2013) [278] Sweden Application of the NMQ in a varied occupational group.…”

“…Ditchen et al [277] focused on the time that workers (190 males) were kneeling during their workday and their subsequent knee problems. Nordander et al [278] analysed the risk factors and musculoskeletal disorders of the elbow and hand of a large sample of workers.…”