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THE RELATION BETWEEN PAIN INTENSITY, DEGREE OF DISABILITY AND QUALITY OF LIFE IN PATIENTS WITH BACK PAIN

Title.

Correlation between pain, disability and quality of life in patients with non-specific low back pain.

Background.

Traditionally it has been believed that in patients with low back pain it is the pain that causes their disability (defined as the limitation in daily activities) and that both factors explain the deterioration in quality of life. However, in recent years, it has been shown that pain intensity and degree of disability are weakly correlated and that more factors are involved, especially of a psychological and social kind. Thus, there are patients with a lot of pain who continue to carry out most of their activities (that is, with little disability) and visa versa. Similarly, the relation between both variables and the deterioration in the quality of life has not been quantified.

For doctors, the priority tends to be to improve pain. Nonetheless, it is useful to identify the aspects which effect the quality of life in patients in order to determine their priorities and to keep them in mind when defining the treatment strategy. Additionally, if the determinants of the quality of life vary over time, identifying these variations may be necessary to optimize the treatment strategies at each moment so as to ensure that they are focused on the most important and relevant aspects in each phase.

Objectives.

1. To quantify the influence of the pain's intensity and duration on the degree of disability.

2. To quantify the influence of the pain's intensity and duration on the quality of life.

3. To quantify the influence of pain and disability on the quality of life.

4. To analyze the influences in terms of the patient's current evolution.

Methodology.

This was a prospective, cohort study in which the correlation between the outcome of several previously validated measuring instruments and the evolution of this correlation over time was studied.

195 subjects participated in the study, who had asked to be attended by their Primary Care physicians in the National Health System for common low back pain ("non-specific low back pain") and who did not suffer radiated pain to the leg.

The patients were attended the day on they requested appointment and 14 days later. On each occasion, the intensity of their pain was appraised (by a visual analog scale), their degree of disability (by the Roland-Morris scale) and their quality of life (by the EuroQol scale).

In the analysis phase, regression models were developed to determine the correlation among the three variables.

Participants along with the Foundation's Science Department.

42 doctors from 7 Primary Care Centers in Mallorca and Research Units of Primary Care of INSALUD of the Balearic Islands; and the Ramón y Cajal Hospital, all associated with the Spanish Network of Researchers in Back Problems.

The study was financed in its entirely by the Kovacs Foundation

Status.

The study has finished and was published by the journal Spine (Kovacs FM, Abraira V, Zamora J et al. Spine: 2004; 29(2): 206-210). In brief, its results show that:

1. In patients with low back pain, the quality of life depends more on the duration than the intensity of the pain. Pain intensity and degree of disability explain only 26% of quality of life the first day that the patient saw the doctor, but at 14 days, they are its primary determinant and explain 56% of its level. That shows the importance of treating the pain as soon as possible. Thus, while acute pain (of less than 14 days) tends to improve spontaneously, measures should be taken to treat it as soon as it extends beyond that period.

2. Although pain intensity is correlated with the degree of disability and quality of life, it is not the only determinant and in fact, one cannot assume that a spectacular improvement in pain necessarily entails a similar improvement in the limitation of daily activities or in the level of quality of life. In fact, a variation of 10% in pain intensity entails only a 3% variation in disability and 3% in quality of life (the first day of pain) or 5% and 4% respectively (14 days later). That also means that these variables must be measured separately when the effect of treatments for low back pain is being evaluated, since a very significant improvement in the intensity of pain may entail unappreciable differences in disability and quality of life.