Background/Purpose:

All-cause mortality in osteoarthritis (OA) is reported to be increased. However, the knowledge about cause-specific mortality in OA is still very limited. Thus, our purpose was to estimate cause-specific mortality in osteoarthritis compared to the general population.

Methods:

We identified all residents in southern Sweden aged 45 to 84 years in 2003. Through the Skåne Healthcare Register we identified those diagnosed with osteoarthritis (OA) in peripheral joints between 1998 and 2003. We followed all residents from 2004 until relocation outside of the region, death, or end of 2014. We classified the underlying cause of death from death certificates into: cardiovascular, neoplasms, diabetes, infections, dementia, digestive, or other causes. For estimation, we used multi-state adjusted Cox proportional hazards models.

Results:

We identified 15 901 patients (mean age [SD] 67 years [10], 41% men) with prevalent doctor-diagnosed OA in knee, 9347 in hip, 4004 in hand and 5447 with diagnosed OA in other peripheral joints among 469 177 residents. For most causes of death in OA patients, we found no increased mortality, with hazard ratios (HR) close to 1. However, for knee and hip OA and cardiovascular death, HRs were non proportional and increased to 1.19 (95%CI 1.10, 1.28) and 1.13 (1.03, 1.24) during 9 to 11 years of follow-up, mostly due to excess mortality from chronic ischemic heart diseases and heart failure in patients with OA (Figure 1 and 2).

Conclusion:

The risk of cardiovascular excess death increases with duration of knee and hip OA. The major contributors are chronic ischemic heart diseases and heart failure. Our results call for improved implementation of guidelines in OA treatment, with major focus on maintaining physical activity and weight-management as well as other preventative measures to reduce cardiovascular deaths.

Figure 1. Cardiovascular mortality in patients with knee OA as compared to the general population – adjusted hazard ratios with 95%CI from Cox regression model during 3 periods of the follow-up time.

*CVD – cardiovascular diseases, IHD – ischemic heart diseases, MI – myocardial infarction

Figure 2. Cardiovascular mortality in patients with hip OA as compared to the general population – adjusted hazard ratios with 95%CI from Cox regression model during 3 periods of the follow-up time.

*CVD – cardiovascular diseases, IHD – ischemic heart diseases, MI – myocardial infarction