The presence of widespread pain is easily determined and is known to increase the risk for persistent symptoms.
The study hypothesis was that people with no or minimal knee osteoarthritis (OA) and high Western Ontario and McMaster Universities (WOMAC) Pain Scale scores would be more likely than other subgroups to report widespread pain.
A cross-sectional design was used.
Data were obtained from the Multicenter Osteoarthritis Study, which includes people with or at high risk for knee OA. The inclusion criteria were met by 755 people with unilateral knee pain and 851 people with bilateral knee pain. Widespread pain was assessed with body diagrams, and radiographic Kellgren-Lawrence grades were recorded for each knee. Knee pain during daily tasks was quantified with WOMAC Pain Scale scores.
Compared with people who had high levels of pain and knee OA, people with a low level of pain and a high level of knee OA, and people with low levels of pain and knee OA, a higher proportion of people with a high level of knee pain and a low level of knee OA had widespread pain. This result was particularly true for people with bilateral knee pain, for whom relative risk estimates ranged from 1.7 (95% confidence interval=1.2-2.4) to 2.3 (95% confidence interval=1.6-3.3).
The cross-sectional design was a limitation.
People with either no or minimal knee OA and a high level of knee pain during daily tasks are particularly likely to report widespread pain. This subgroup is likely to be at risk for not responding to knee OA treatment that focuses only on physical impairments. Assessment of widespread pain along with knee pain intensity and OA status may assist physical therapists in identifying people who may require additional treatment.