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Occupational Medicine Advance Access originally published online on June 18, 2007
Occupational Medicine 2007 57(6):430-437; doi:10.1093/occmed/kqm048
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© The Author 2007. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

Piecework, musculoskeletal pain and the impact of workplace psychosocial factors

Rosie J. Lacey, Martyn Lewis and Julius Sim

Primary Care Musculoskeletal Research Centre, Keele University, Keele, Staffordshire ST5 5BG, UK

Correspondence to: Julius Sim, Primary Care Musculoskeletal Research Centre, Keele University, Staffordshire ST5 5BG, UK. Tel: +44 1782 584253; fax: +44 1782 584255; e-mail: j.sim{at}keele.ac.uk


   Abstract
Top
 Abstract
Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
 References
 
Aim To investigate the impact of piecework on musculoskeletal pain and general health, and the influence of perceived workplace psychosocial factors on any such associations, in a general UK population.

Methods A questionnaire was mailed to an age-stratified random sample of 10 000 adults aged 18–75 in North Staffordshire, UK. Respondents reporting a current main job were asked if this job was paid by a piecework system. Health measures were (i) number of pain areas according to a body manikin and (ii) general health (SF-12v2). Other measures included questions on occupational history and psychosocial aspects of the work environment.

Results The adjusted response was 54%. A total of 1193 respondents reported a current main job, of whom 201 (17%) reported piecework. Pieceworkers were more likely to be older (P < 0.05), male (P < 0.001) and in lower socioeconomic groups (P < 0.001) than non-pieceworkers. Piecework was associated with perceptions of a poor psychosocial working environment, more pain areas (P < 0.05), more elbow (P < 0.01), forearm (P < 0.001) and hand pain (P < 0.05), and a lower physical health score (SF-12v2; P < 0.01), but no difference in mental health score (P = 0.60), compared with non-pieceworkers. After controlling for psychosocial factors, and socioeconomic group, the associations between piecework and pain areas, or physical health, were no longer statistically significant.

Conclusions These results show that piecework was associated with poorer self-reported general physical health and more areas of pain, which may be attributed to low socioeconomic group, and workplace perceptions of little job control, high physical demand and little supervisor support.

Keywords      Cross-sectional study; health indicators; musculoskeletal; occupational stress; pain


   Introduction
Top
 Abstract
 Introduction
Methods
 Results
 Discussion
 Conflicts of interest
 References
 
Piecework is the term used for a system of payment whereby employees are paid according to the amount of work produced [1]. Historically, piecework has existed in low-paid manual industries such as garment workers and pottery (ceramic) workers [2,3]. However, although it may appear to be an outdated form of employment in 21st century Western cultures, piecework is increasingly applied to home-based workers (‘outworkers’) and seasonal and migrant agricultural workers [4–6]. This is of current relevance since piecework, often low paid and temporary, is one aspect of the job insecurity that has emerged with greater labor market flexibility and deregulation of employment contracts [7].

Recent studies have reported that a piecework system of payment is associated with increased risk of injury in outworkers in the Australian clothing industry and in female agricultural workers in California [4,6]. Piecework has also been shown to be a risk factor for hand paresthesiae in vineyard workers in France [5]. However, to our knowledge, there is no information regarding the current impact of piecework on self-reported pain, and general physical and mental health, in a general population. Since there is evidence that a system of piecework payment encourages missed breaks and increased work pace, as workers try to maximize output (and hence earnings) in proportion to time [5,8], it is also important to investigate the psychosocial factors perceived by workers in a piecework environment. Could a poor psychosocial working environment help to explain a possible relationship between piecework and workers' pain and general health?

The objective of our study, therefore, was to determine the association between piecework and musculoskeletal pain, and general physical and mental health, in an adult general population, and investigate the extent to which this might be influenced by demographic and socioeconomic characteristics, and workplace psychosocial factors.


   Methods
Top
 Abstract
 Introduction
 Methods
Results
 Discussion
 Conflicts of interest
 References
 
In this cross-sectional study, a postal questionnaire was used to measure the 4-week period prevalence of pain, and obtain details of occupational history. North Staffordshire Local Research Ethics Committee granted approval for the study and data collection occurred from 2001 to 2002. The results presented in this paper arise from a broader study of occupational factors associated with neck and upper limb pain.

The sampling frame consisted of the general practice (GP) database of the North Staffordshire District Health Authority, UK. Approximately 98% of the UK population is registered with a GP [9], and therefore the GP register is regarded as being representative of the general population in the UK [10]. We took a random sample of 10 000 adults in equal numbers from each of four age groups: 18–44, 45–54, 55–64 and 65–75. Fourteen of the 300 people who had participated in the previous pilot study, and 14 people who had died or departed from a GP list, were excluded and replaced with age-, gender- and GP-matched individuals from the population. Following initial mailing of the questionnaire, non-responders were followed up twice, at two weekly intervals.

The main health outcome measures in this study were (i) number of areas of pain lasting for 1 day or longer in the past 4 weeks shaded on a blank body pain manikin (the 44 body areas on the manikin were those in the template used to score widespread pain, derived from Macfarlane et al.) [11,12] and (ii) general health, according to the Short Form 12 (SF-12v2) [13,14], which comprises two summary scores: physical component summary (PCS) and mental component summary (MCS). The SF-12 is a generic health status measure previously validated in general populations [13,15].

Subjects were asked to complete a grid question, which asked for details of up to five most recent jobs (job title, area of work, start date, end date) held for at least 12 months. From this information, the job held for the longest time was marked as the respondent's ‘main job’. We asked respondents if this main job was paid by a piecework system: ‘In this job, were you paid according to your rate of work (for example, piecework)?’. The piecework question had undergone previous cognitive testing with patients at a rheumatology clinic during the pre-pilot study of the questionnaire, and was found to be comprehensible by all 13 patients who took part. Repeatability of the questionnaire (including the piecework question) was assessed during a two-phase pilot study, prior to the main study [16]. The repeatability of the piecework question was good, with 94% agreement between the two phases of the pilot study [kappa = 0.85, 95% confidence interval (CI) 0.68, 1.00].

Respondents' perceptions regarding psychosocial aspects of their main job were collected using questions similar to those of other studies [17,18], based on Karasek's demand–control model [19]. Scoring was based on a five-point adverbial scale (‘none of the time’ to ‘all of the time’). The questions were as follows:

(i) Can/could you control the way you worked in this job?
(ii) Is/was your work physically demanding in this job?
(iii) Do/did the tasks and activities that you perform/performed in this job change during your time in this job?
(iv) Do/did you get job satisfaction from your work in this job?
(v) On the whole, are/were your supervisors or managers supportive in this job?

Occupational data were classified according to SOC2000 [20], using job title and area of work provided by respondents. SOC2000 occupational coding was used to derive the National Statistics Socioeconomic Classification (NS-SEC) [21], which is a measure of both social class and socioeconomic group. Demographic data were also collected.

The sections of the questionnaire were arranged such that outcome data were collected prior to exposure data, in order to reduce potential bias from order effects.

Statistical analysis was confined to respondents whose main job was also their current job for the following reasons: (i) to ascertain the number of people currently engaged in piecework, (ii) to minimize potential recall bias, since workers would be expected to have better recall of their current job than of previous jobs and (iii) because we asked about recent pain, i.e. pain in the past 4 weeks.

Sociodemographic and workplace psychosocial characteristics were compared between piecework and non-piecework respondents, using chi-square tests. Pieceworkers and non-pieceworkers were compared in terms of their average SF-12 MCS and PCS scores using linear regression, and estimates of the mean differences are presented with 95% CIs. As the data on number of pain areas were skewed, the Mann–Whitney U-test was used to compare the number of pain areas between pieceworkers and non-pieceworkers. For the same reason, the data on number of pain areas were split into four arbitrary ordinal categories (0, 1–3, 4–6 and ≥7), and estimates of the associations with piecework were generated through ordinal regression (with logit link function) and expressed as odds ratios (ORs) with 95% CIs; the assumption of proportional odds was tested for this analysis [22,23]. Cross-tabulations and chi-square tests were used to evaluate the associations between piecework and regional body pain.

A final multivariable analysis was carried out to investigate the associations between psychosocial factors and body pain and general health. Linear regression was used when the outcome of interest was the SF-12 summary scales. Ordinal regression (with logit link function) was used when the outcome of interest was number of pain categories; the assumption of proportional odds was tested for this analysis. The analysis was performed both with and without adjustment for sociodemographic and other psychosocial covariates.

Statistical analysis and random sampling were carried out using SPSS version 13 (SPSS Inc., 2004).


   Results
Top
 Abstract
 Introduction
 Methods
 Results
Discussion
 Conflicts of interest
 References
 
The questionnaire was returned by 5133 people, a response of 54% following adjustment for deaths and departures. A total of 4040 respondents had complete data for their main job, of whom 3514 (87%) completed the question on piecework. The sample analyzed were those 1193 respondents currently employed in their main job who completed the piecework question. A total of 201 (17%) reported piecework (being paid according to their rate of work) in their current main job (direct age-standardized prevalence: 16%).

Table 1 compares the sociodemographic profiles of piecework and non-piecework respondents. Pieceworkers were more likely to be of older working age, male and classified in a lower socioeconomic group (i.e. routine and manual occupations), compared with non-pieceworkers.


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  		Table 1. Sociodemographic and socioeconomic characteristics of pieceworkers and non-pieceworkers

 
Pieceworkers reported worse psychosocial conditions in the workplace than non-pieceworkers (Table 2). Respondents who reported doing piecework perceived themselves as having less control over the way they worked, higher physical demand, lower job satisfaction and less supervisor support than non-pieceworkers. Also, proportionally more pieceworkers reported having no change in their work tasks.


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  		Table 2. Associations between piecework and psychosocial factors in the workplace

 
Unadjusted analyses showed that, overall, pieceworkers reported significantly lower mean general physical health (PCS) score than non-pieceworkers (t = 3.088, P < 0.01), although there was no significant difference in mean general mental health (MCS) score (t = 0.520, P = 0.60; Table 3). Pieceworkers shaded more areas of pain on the body manikin than non-pieceworkers (Mann–Whitney U-test, P < 0.05).


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  		Table 3. Associations between piecework and number of areas of pain and general health status

 
A series of adjustments was carried out to investigate whether the associations between piecework and number of pain areas and general physical health could be explained by other factors. There was little change in the magnitude of the associations after adjusting for age and gender only. However, after additionally adjusting for socioeconomic class using NS-SEC as a covariate, and after further adjusting for workplace psychosocial factors, the associations with piecework were lower (Table 3).

Pieceworkers were significantly more likely to report elbow, forearm and hand pain than non-pieceworkers. There was no significant difference in the reporting of neck, shoulder, low back, hip or knee pain (Table 4).


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  		Table 4. Associations between piecework and regional pain

 
Little job control, little supervisor support and a perception that work is physically demanding were significantly associated with an increased number of pain areas and lower mean SF-12 PCS scores (Table 5). This was the case in the unadjusted analyses and also after adjusting for age, gender, NS-SEC category and psychosocial factors in multiple regression analyses. Additional analyses of all respondents with a main job, either current or past, revealed similar associations. For example, in all those with a main job, the perception of little job control was significantly associated with an increased number of pain areas (adjusted OR: 1.58; 95% CI 1.39, 1.81), compared with that for respondents with a current main job (1.43; 1.13, 1.81).


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  		Table 5. Association between workplace psychosocial factors and number of areas of body pain and general physical health

 

   Discussion
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
Conflicts of interest
 References
 
This study has shown, for the first time, that workers whose jobs involved piecework reported poorer general physical health, and more areas of pain (particularly forearm, elbow and hand pain) than non-pieceworkers. However, these associations were accounted for by perceptions of a poor psychosocial working environment and low socioeconomic status, suggesting that these factors, rather than piecework itself, may explain both the increased number of areas of pain and the poorer physical health experienced by pieceworkers.

In our North Staffordshire stratified general population sample, 16% of those with a current main job reported piecework. North Staffordshire is an industrialized and relatively poor area, socioeconomically, which may explain this high figure, although we have been unable to source any recent comparable piecework data. Pieceworkers were employed almost exclusively in skilled trade occupations or as process, plant and machine operatives, two occupational groups that typically include manual workers. They were also at least twice as likely to be male, compared with non-pieceworkers, which is in agreement with a recent labor market analysis of UK workers in these two occupational groups [24]. Those reporting piecework were of older working age suggesting that, currently, piecework is possibly a system of employment that is either less attractive to younger people or that the jobs in which they are employed are less likely to be paid on a piecework basis.

Our data showed that the association between piecework and an increased number of areas of pain was reduced following sequential adjustment for socioeconomic category and psychosocial factors. Previous research has also suggested that psychosocial factors of the work environment are linked with musculoskeletal pain [17,18,25–27], although not all studies agree on the specific factors [28], or their definitions. Similarly, our results showed that the association of piecework with poor general physical health was accounted for by socioeconomic status and psychosocial factors. Although a different measure (of social class) was used, social deprivation has been reported to be associated with musculoskeletal symptoms in a population survey of adults by Urwin et al. [29]. Interestingly, our data also revealed that pieceworkers did not have significantly poorer general mental health scores than non-pieceworkers, as measured by the SF-12 MCS score. It has been suggested that those who work on piece rates are more likely to carry on with their work despite injury or symptoms [5], since stopping for a break or reducing their work pace would mean reduced pay [4]. This, in turn, may require a certain level of mental strength to ‘carry on regardless’. It may also reflect a healthy worker effect, whereby only those who are able to cope mentally remain in this type of work. However, the sample in our study was taken from a community, not a workplace, setting that comprised a large number and wide range of occupations, thereby reducing the impact of the healthy worker effect.

Having found that pieceworkers reported more areas of pain on the body manikin than non-pieceworkers, we identified that the areas were more likely to be within the distal upper limb (forearm, elbow or hand) than in other parts of the body. Pain in the forearm, elbow or hand has been associated with repetitive work in several manual industries, e.g. the pottery industry [30], the fish processing industry [31] and garment workers [32], in which piecework may occur. Indeed, it has been suggested that piecework payment systems may exacerbate musculoskeletal overuse [6], because they reinforce a fast work pace and encourage the missing of breaks, both undesirable in respect of musculoskeletal disorders [8]. These circumstances may, in turn, lead to injury. Evidence for this comes from a previous study of outworkers who reported more than three times the amount of injury compared with factory workers; the most significant factor explaining this difference was the piecework payment system of outworkers [4]. Roquelaure et al. [5] also reported piecework to be associated with a higher prevalence of hand paresthesiae, suggesting that this mode of payment encouraged faster work and neglect of hand pain.

Multivariable analyses revealed three specific workplace psychosocial factors that were independently associated with an increased number of areas of pain and poorer general physical health: perceptions of little job control, high physical demand and little supervisor support. Potentially, it is possible to improve workers' perceptions of job control and supervisor support, through modification of work organization and improved management; however, workers' perceptions that some piecework environments are physically demanding may be more difficult to alter because workers may resist change to a system that enables them to maximize their earnings [4,8].

Though age and gender were not major confounders of the association between piecework and health outcomes, there was some indication that they were effect modifiers. When stratifying by age, associations with number of pain areas and SF12-PCS scores were significant only within the age categories 45–54 and 55–64 years. Also, significant associations with both outcomes were only observed for men. This tends to suggest that the adverse effect of piecework (and the psychosocial factors to which this may be attributed) may be more pronounced in certain subgroups, for example, men aged 45–64 years. By contrast, socioeconomic status was a confounder of the association, partially accounting for the observed link between piecework and poorer health. However, the diminished association resulting from the inclusion in the model of socioeconomic status was fairly stable across the different social class categories. This indicates that piecework, and notably the associated psychosocial workplace factors, has a negative impact on health irrespective of occupational standing, though piecework is more commonly a feature of manual occupations than of non-manual occupations.

The strengths of this study are that it is a population study, and not industry-specific. It also includes both genders, whereas many previous studies of industries in which piecework occurs have been female-specific [2,31,32]. This study focused only on current workers as we felt it was important to determine the extent to which people were currently engaged in piecework, if at all. However, in an additional multivariable analysis, similar associations were obtained for all respondents with a main job, past or current. In order to minimize potential recall bias in this study, we firstly included respondents reporting a current main job, since current workers did not have to rely on their memory of the aspects of a job performed or experienced many years ago. Secondly, we attempted to reduce recall bias by gathering all symptom information before that related to potential risk factors in the questionnaire.

The original sample size of 10 000 was determined in relation to a broader epidemiological study [30]. In the present study, the sample comprised a subgroup of the original cohort; specifically, 1193 currently employed respondents whose job was historically the job they had held for the longest time, and who responded to the question on whether or not their job was on a piecework basis. Given that 201 responded positively and 992 responded negatively to working on a piecework basis, we had 90% power to detect an effect size of 0.25—within the range of a ‘small’ effect [33]—in our continuous outcome measures, at a two-tailed 5% significance level.

In conclusion, this study has highlighted that ~16% of current workers in North Staffordshire reported being paid according to a piecework system, and that these workers were more likely to have distal upper limb pain and experience an adverse psychosocial working environment. We have shown that it is the perceptions of little job control, high physical demand and little supervisor support experienced in a piecework environment that account for the increased reporting of body pain, particularly widespread pain, and poorer general physical health. These findings suggest that there is potential for reducing pieceworkers' pain and improving their general physical health, by modification of workplace psychosocial factors, such as improved work organization and management. However, the perceived physical demands of piecework environments may be difficult to improve if workers are reluctant for a system that enables them to maximize their earnings to be changed. Therefore, regulation of employment contracts may be the area in which intervention is most likely to be effective to reduce the adverse effects of the piecework environment. More research is needed to examine the current prevalence of piecework, its impact on pain and general health and the influence of workplace psychosocial factors on these associations, in other general populations, both in the UK and worldwide.


Key points
  • Little is known about the impact of piecework on pain and health status in the general population.
  • In a survey of ~5000 UK adults, piecework was found to be associated with more pain areas, poorer physical health, which may be attributed to low socioeconomic status, and perceptions of a poor psychosocial working environment.
  • Modification of the working environment and regulation of employment contracts may be a means of reducing the adverse effects of piecework.

 


   Conflicts of interest
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
References
 
None declared.


   Acknowledgements
 
We wish to thank North Staffordshire Medical Institute for funding the study; Giri Rajaratnam and Joan Bentley for facilitating access to the North Staffordshire health authority database; Gary Macfarlane for advising on the questionnaire; M. E. F. McCarthy and partners and Elaine Hay and colleagues at the Haywood rheumatology clinic for assisting in the pilot study; Cath Young for the coding of occupational data; Tracy Whitehurst, Rachel Birtles, Helen Ogden and other colleagues for help with the database and administration of the survey.


   References
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
 References
 

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