Knee osteoarthritis and all-cause mortality: the Wuchuan Osteoarthritis Study.

BACKGROUND

Previous studies showed that knee osteoarthritis (OA) is associated with increased mortality in Caucasians. While prevalence of knee OA is higher in Chinese than in Caucasians, no study has examined whether knee OA increases mortality in Chinese population.

METHODS

Between 8/2005-10/2005 1025 residents aged ≥50 years were recruited in randomly selected rural communities in Wuchuan, China. Subjects completed a home interview and had weight-bearing posteroanterior semiflexed view of radiographs at tibiofemoral joints and skyline view of radiographs at patellofemoral joints, and were followed until end of 2013. A knee was defined as having radiographic osteoarthritis (ROA) if either Kellgren/Lawrence (KL) score at tibiofemoral joint ≥2 or presence of OA at patellofemoral joint based on OARSI criteria. Symptomatic knee osteoarthritis (SxOA) was defined if both pain (i.e., knee pain occurred on most days in past month) and ROA were present at the same knee. We examined the relation of knee SxOA and knee ROA to the all-cause mortality, respectively, using Cox-proportional hazard models adjusting for potential confounders.

RESULTS

Over the follow-up period 99 subjects died. The mortality rates were 32.6 (95% confidence interval (CI): 19.6-54.0) and 10.9 (95% CI: 8.8-13.5) per 1000 person-years among subjects with and without SxOA, respectively. Multivariable adjusted hazard ratio of all-cause mortality for knee SxOA was 1.9 (95% CI: 1.0-3.5). However, no such association was observed for knee ROA (hazard ratio = 1.2, 95% CI: 0.7-1.9).

CONCLUSIONS

Knee SxOA was associated with an increased risk of all-cause mortality among the residents in the rural areas of China.