Correlation between pain, disability, and quality of life in patients with common low back pain.

Study Design: Correlation among previously validated questionnaires.

Objectives: To determine the correlation between pain, disability, and quality of life in patients with low back pain.

Summary Of Background Data: The Visual Analogue Scale (VAS), and the Roland-Morris (RMQ), Oswestry (OQ), and EuroQol (EQ) Questionnaires are validated instruments to assess pain, low back pain-related disability, and quality of life.

Methods: The study was done in the primary care setting, in Mallorca, with 195 patients who visited their physician for LBP. Individuals were given the VAS, RMQ, OQ, and EQ on their first visit and 14 days later.

Results: Median duration of pain when entering the study was 10 days (P25,P75: 3, 40). On day 1, simple correlation was r = 0.347 between VAS and RMQ, r = -0.422 between VAS and EQ, and r = -0.442 between RMQ and EQ. On day 15, simple correlation was r = 0.570 between VAS and RMQ, r = -0.672 between VAS and EQ, and r = -0.637 between RMQ and EQ. Multiple linear regression models showed that, on day 1, the VAS score explains 12% of the RMQ score and the VAS and RMQ scores explain 27% of the EQ score. On day 15, the VAS score explains 33% of the RMQ score, and the VAS and RMQ scores explain 58% of the EQ score. On day 1, a 10% increase in VAS worsens disability by 3.3% and quality of life by 2.65%. On day 15, a 10% increase in VAS worsens disability by 4.99% and quality of life by 3.80%. Prestudy duration of pain had no influence on any model. All these correlation coefficients and models are significant at the P < 0.001 level. The OQ had lower correlation values with the other three scales, and only two of them were significant.

Conclusion: Clinically relevant improvements in pain may lead to almost unnoticeable changes in disability and quality of life. Therefore, these variables should be assessed separately when evaluating the effect of any form of treatment for low back pain. The influence of pain and disability on quality of life progresses while they last, and doubles in 14 days. In acute and subacute patients, this increase is not dependent on the previous duration of pain.