DIFFERENCES IN PREVALENCE OF SELF-REPORTED MUSCULOSKELETAL SYMPTOMS AMONG COMPUTER AND NON-COMPUTER USERS IN A NIGERIAN POPULATION: A CROSS-SECTIONAL STUDY By

Background: Literature abounds on the prevalent nature of Self Reported Musculoskeletal Symptoms (SRMS) among computer users, but studies that actually compared this with non computer users are meagre thereby reducing the strength of the evidence. This study compared the prevalence of SRMS between computer and non computer users. Methods: A total of 472 participants comprising equal numbers of age and sex matched computer and non computer users were assessed for the presence of SRMS. Information concerning musculoskeletal symptoms and discomforts from the neck, shoulders, upper back, elbows, wrists/hands, low back, hips/thighs, knees and ankles/feet were obtained using the Standardized Nordic questionnaire. Results: The prevalence of SRMS was significantly higher in the computer users than the non computer users in both the 7 day (X 2 = 39.11, p = 0.001) and 12 month durations (X 2 = 53.56, p = 0.001). The prevalence ratio of the computer user to the non computer user was > 2 for both time frames. Over the 7 day duration, the neck (33.9%) and low back (11.4%) had highest prevalence of SRMS for the computer and non computer users respectively. However, the neck was the site with most prevalent SRMS for both computer (64.0%) and non computer (33.9%) users in the 12 month duration. Ankle was least reported (6.4%) as the site with SRMS in the computer users while elbow was least reported (3.0%) in the non-computer users. Conclusion: The prevalence of SRMS over the 7 day and 12 month durations was significantly higher in the computer users than the non computer users and the neck was the site with the highest prevalence of SRMS for both durations in the computer users. Introduction The availability of computers have made varieties of work faster, easier, neater and less frustrating to the users. Computers (also called video display terminals) have become increasingly common in both workplaces and homes over the past 20 years [1]. However, the use of computers is not without its menacing side; an example of which is the predisposition to musculoskeletal disorders by the users. Sustained pain in the upper extremity and neck regions and specific musculoskeletal disorders, such as wrist tendonitis, epicondylitis, and trapezius muscle strain are high among computer users [2]. Non-specific forearm pain has been reported as a common complaint among computer workers with high job demands, time pressure, and female gender being some of the risk factors [3]. More reasons have been adduced for musculoskeletal problems in computer users. Frequent computer-related activities have been shown to be an independent risk factor for neck shoulder pain and low back pain [4], while the prevalence and incidence of forearm pain was shown to be independently related to the intensive use of the mouse device and to a lesser extent to keyboard usage, female gender, high job demands, and time pressure at work [3]. In adolescents according to Hakala et al [4], daily use of computers exceeding 2– 3 hours seems to be a threshold for neck shoulder pain and exceeding 5 hours for low back pain. In view of the widespread use of the computer, even relatively small risks associated with their use would have important public health implications, and interventions that result in decreased risk would have great public health benefits [1]. Different prevalence statistics on the SRMS experienced by computer users have been documented for different anatomical parts of the body. The seven days prevalence of moderate to severe forearm pain in computer users as documented by Kryger et al [3] was 4.3% while one year incidence of reported symptom cases was 1.3%. The prevalence of weekly severe pain was low, the incidence of prolonged neck pain was 0.31%, and the incidence of prolonged shoulder pain was 0.23% [5]. The baseline prevalence of hand/wrist or elbow pain was 24% (moderate pain in last 7 days) and after one year new cases arose in 7.7% of the population [6]. Andersen et al [5] reported the prevalence of possible carpal tunnel syndrome as 1.4–4.8% and the incidence of new cases in 12 months as 5.5% based on symptoms, and 1.2% when confirmed by a clinical interview. According to Hakala et al [4], computer-related activities may explain the increase of neck shoulder pain and low back pain presented in the 1990s and the beginning of 2000 in the Finnish population. In a two year study of 3475 computer users in Denmark, self-reported use of a computer more than 75% time, compared with 50% of time, increased the risk of hand/wrist symptoms, while using a mouse for 50% of time, compared with 25% of time, increased risk for female users [7]. A systematic review also concluded that there is consistent evidence of a positive relationship across numerous prospective and cross-sectional studies with increased risk of disorders most pronounced beyond 20 hours/week of computer use or with increasing years of computer work [8]. However, most of the prevalence reports on SRMS and computer use have been conflicting with results as varied as the number of studies carried out in this area. A more recent study for instance has questioned the beliefs about the prevalence of adverse effects from the use of computers. Andersen et al [9] reported that the common opinion stating that computer use has adverse health effects is questionable. According to the authors, most computer workers have no or minor neck and shoulder pain complaints, few experience prolonged pain, and even fewer, chronic neck and shoulder pain. Despite the increasing number of computer users and the abundance of evidence suggesting that SRMS are present in computer users, there are very few readily available and conclusive studies that have compared these prevalence with that of the non computer users. Most previous studies failed to establish whether the prevalence was peculiar to computer users. In view of this, it is difficult stating whether the prevalence of SRMS in computer users is the same or different from non computer users. This study was hence designed to find if any difference existed in the prevalence of SRMS between the computer and non computer users. Methods Study design: This was a cross sectional study computer and non computer users. Recruitment of study population: A total of 300 questionnaires were distributed to computer users based on a calculated representative sample size of 295.65 [10]. Out of the 300 questionnaires distributed, 236 were returned yielding a response rate of 78.1%. Subsequently, the questionnaires were administered on 236 age and sex matched non computer workers who were selected purposively and who consented to participate in the survey giving a total of 472 participants in the two groups. The computer users were recruited purposively from the Ladoke Akintola University of Technology Teaching Hospital, Osogbo; College of Health Sciences, Osogbo; Power Holdings Company of Nigeria, Osogbo; Bureau of Computer Services and Information Management, Osogbo and computer operators in private computer business centres in Osogbo all in Osun State, South-Western Nigeria. For this study, the computer users were the workers whose employment were anchored essentially on the use of the computer, while the non computer users who served as the control group were individuals who only used the computer casually for activities like e-mailings and for less than 30 minutes in a week. They were members of staff of the five centres from where the computer users were recruited and they were recruited purposively into the study. Data collection procedure: A letter of transmission explaining the purpose and nature of the study was attached to the questionnaire. This also contained adequate instructions on how to fill the questionnaire. The SRMS were assessed using the self administered Standardized Nordic questionnaire developed by Kuorinka et al [11]. All the participants were able to read and understand the questionnaire in English language; hence we did not have to subject the instrument to translations into local languages. The participants were queried concerning musculoskeletal symptoms on the neck, shoulders, upper back, elbows, wrists/hands, low back, hips/thighs, knees and ankles/feet in the form of musculoskeletal symptoms (troubles, aches or pain) felt within seven days and twelve months prior to the study. The choice of the time frames was predetermined and was adapted from a previous study [3]. This presented the opportunity for the documentation of the current (short term) and past (long term) SRMS. All the participants were asked questions such as “Have you at any time during the last 12 months had trouble (ache, pain, discomfort) in your neck, shoulders, elbows etc?” They were also asked whether they had any troubles in the last seven days. They were also asked to indicate using a diagram on what part of the body the pain, ache or discomfort was being felt. The self reported time duration during which computer was used by each participant was also assessed. Further information was also documented on the demographic characteristics of the participants. The questionnaire was administered on the participants following an approval granted by the joint University of Ibadan and University College Hospital Ethical Review Committee (Protocol ID: UI/IRC/06/0060). The consent of the appropriate officers in charge of each of the establishments where the study took place as well as that of the participants was also obtained. Statistical analysis: The difference in the seven day and 12 month prevalence of SRMS between the computer and non computer users as well as the differences within the computer group and the non computer group were compared using the Pearson Chi square test. The prevalence is presented in the form of percentage and frequency distributions. The prevalence ratio was calculated using a 2 by 2 table, as the ratio of the prevalence of SRMS in the computer user group divided by the prevalence of SRMS in the non computer user group. Data were analysed using the SPSS Version 15.