Materials and methods

Results

As previously reported, the one month prevalence of “regional pain” (neck/shoulder or low back pain) was 37% (n=4366), while 2042 patients (17%) reported “widespread pain”.1 Among the 6408 respondents who had experienced non-inflammatory musculoskeletal pain, 2909 (45% (95% CI 44% to 47%)) had consulted a GP for their musculoskeletal pain during the past 12 months, 3357 (52%) reported that they had not consulted a GP, while 142 (2%) did not respond to this question. Consulting was more common among women (48%) than men (42%). As shown in tables 2 and 3, all included variables, except for area of residence, smoking status, and amount of regular exercise, were significantly associated with consulting for both sexes. Multivariate analyses disclosed that among the predisposing factors, the odds of consulting were significantly increased by having a higher age, by having a lower degree of formal education, and by being a pensioner or on sick leave. For both men and women pain intensity was the factor most prominently associated with consulting, adjusted OR=2.4 and 2.6, respectively. Also, patients with widespread pain were more likely to consult than those with regional pain, as were those with a greater than median MHAQ score. As shown in the right hand columns of tables 2and 3, mental distress was not significantly associated with consulting in men, while chronicity was not significantly associated with consulting in women.

Subgroup analyses showed that for chronic pain, the level of mental distress was significantly associated with consulting in both sexes, while consulting for non-chronic pain was not (table 4). Level of mental distress was significantly associated with consulting for both regional and widespread pain in women, but not in men (table5).

Discussion

This study showed that about half of those who reported non-inflammatory musculoskeletal pain had consulted a GP during the past year. Pain intensity was the factor most prominently associated with consultation. Mental distress was significantly associated with consultation for chronic pain, and more so for women than for men.

Even though this study provides information about consultation behaviour in a large general population, it has several limitations. As the time sequence in a cross sectional survey cannot be established, the significant associations found in this study may not be causal. The present results can therefore only be considered as generating a hypothesis, and should be tested by following up subjects prospectively. We also used shortened instruments to obtain data on levels of mental distress and disability (SCL-5 and MHAQ) because the original questionnaires (SCL and HAQ) were considered too extensive for a population survey. The scores of the SCL-5 and MHAQ had distributions skewed to the left, and are probably insensitive to lower levels of mental distress and disability. The association between consulting and disability and mental distress may therefore be underestimated in this study. Even if pain, disability, and mental distress were independent predictors for consulting, one might expect that these variables are strongly correlated. A correlation analysis showed that pain and disability was moderately correlated (r=0.42), whereas mental distress was weakly correlated with the two other variables (r=0.16–0.18), indicating that mental distress, on the one hand, and pain and disability, on the other, represent different dimensions.

The fact that 40% did not respond to the survey may be a possible source of bias. The non-responding rate was generally higher among men than women, and also somewhat higher among unmarried and divorced than married. In our previously published study1 the prevalence rates were therefore computed by weighting the subjects in the survey to the total population in each of the 16 age-sex-county strata. The corrected prevalence estimates deviated only 0.3% from the crude rates. One may also expect that those who did not respond to the survey were less likely to have musculoskeletal pain than those who did. In this study the prevalence of pain among those responding before the reminder was about 2% higher than among the respondents after the reminder. Based on the assumption that the prevalence among the non-respondents was 3% lower than those who responded after the reminder, Statistics Norway estimated the present prevalence rates to be 1.7% too high at the most (unpublished data). On the other hand, a Norwegian study has shown that the prevalence of musculoskeletal pain tended to be underestimated in questionnaires.15 We therefore think that the effect of any selection bias on the reported prevalence rates is unlikely to be large. However, as neither the pain duration (chronic v non-chronic) nor location (widespread v regional) is validated, these differentiations and the corresponding subgroup analyses may be hampered by information bias. The fact that the consultation rates are self reported may also be a potential source of information bias. Previous research has shown a disparity between patient self reports and documented records of consultation for low back pain.16 On the other hand Hillmanet al reported similar consultation rates for low back pain as this study, and found that false positive and false negative results seemed to cancel each other out, alleviating the necessity to adjust the self reported consultation estimates.17

Our results suggest that consultation for chronic non-inflammatory musculoskeletal pain was associated with greater mental distress. This compares well with the study by Waxman et al, who found that psychosocial factors play a more important part in consultation for chronic than for acute low back pain.18 Our finding that the association between mental distress and consulting was stronger for women than men is also supported by the study of Macfarlane et al, who found that consultation for chronic widespread pain was associated with a significant increase in psychological disturbance in women but not in men.19

The present findings may have implications both from a public health perspective and in a clinical setting. Firstly, the odds of consulting increased significantly with lower levels of formal education. The level of formal education is a useful and widely applied marker of socioeconomic status, and our findings compare well with those of Walshet al,16 Szpalskiet al,20 and Dexter and Brandt.21 A low level of education is also associated with an increased prevalence of musculoskeletal disorders.1 ,22 Thus it seems that not only are subjects with lower levels of formal education at higher risk of developing musculoskeletal pain but they are also less able to cope with the complaints on their own. From a public health perspective this fact represents a great challenge.

Secondly, the association between mental distress and consulting for chronic pain may be important in a clinical perspective. The role of primary care traditionally has been management of pain and disability, but our results suggest that patients with chronic musculoskeletal pain also need psychological support. There is now increasing evidence that “chronic pain is not the same as acute pain lasting longer”,23 and the role of psychosocial factors in chronic back pain is also emphasised in newer clinical guidelines.24

About half of those who had experienced non-inflammatory musculoskeletal pain had consulted a GP in the past year, and this study confirms that such symptoms cause many visits in primary care. Although the cross sectional nature of this study did not allowed us to investigate the temporal relation between symptom onset, mental distress, and consultation, our results support the suggestion that psychosocial factors should be considered in the management of chronic musculoskeletal pain.