Purpose: To understand prognosis for alleviation of pain measured 2 years post-op using quality of life data collected 2 weeks following surgery for knee osteoarthritis.

Methods: 180 patients with knee osteoarthritis underwent 1 of 3 surgical procedures for relief of pain and to improve functional status. Of these, 133 completed all self-reports of pain intensity during the course of 2 years of follow-up. Growth mixture modeling revealed 4 classes of patients. For 2 of these classes, a “low” pain group and a “high” pain group, 2-week pain values (average scores of 11.0 and 37.6, respectively; 0-low pain; 50-high pain) were predictive of their 2-year pain values (13.7 and 32.8, respectively).

However, most patients undergoing surgery (73%) experienced moderate levels of knee pain measured 2 weeks post-op. For these patients, the prognosis over the next 2 years was characterized by 1 of 2 distinct profiles; those who reported pain that became progressively worse versus those who reported pain that progressively improved. Although similar at 2 weeks, the groups had mean 2-year pain ratings of 35.9 and 11.0, respectively. Logistic regression revealed that patients' 2-week post-op evaluations of non-pain symptoms and operation success were highly predictive of whether pain became progressively worse or improved over the subsequent 2 years. On a 0-10 scale, where 0 is indicative of being bothered by non-pain symptoms and perceptions of operation failure, a 1-point increase was associated with a 25% increase in the odds of being classified into the group experiencing pain relief at 2 years (p<.05)

Conclusions: Understanding prognosis helps guide medical decisions with regard to the need for future additional intervention. By using data collected at 2-weeks post-op, it is possible to identify a subset of patients for whom additional intervention might be considered. Understanding the physical and psychological determinants for judgments of non-pain symptoms and operation success at 2 weeks holds promise for explaining why measures taken at 2 weeks are predictive of outcomes 2 years later, and for informing decisions about appropriateness of surgery and/or additional interventions.