To What Extent Is Severe Osteoarthritis Preventable?

Occupational and Non-Occupational Risk Factors for Knee and Hip Osteoarthritis

Tea Kontio; Markku Heliövaara; Eira Viikari-Juntura; Svetlana Solovieva

Disclosures

Rheumatology. 2020;59(12):3869-3877. 

In This Article

Results

Description of Sample

During the follow-up, 150 (3.2%) persons were hospitalized due to knee OA and 87 (1.9%) due to hip OA (Table 1). Persons hospitalized due to knee or hip OA were older at baseline and more frequently overweight or obese than persons not hospitalized. Hospitalizations due to knee OA were more common among women than men, while there was an opposite trend for hip OA.

Risk Factors for First Hospitalization Due to Knee OA

The risk of hospitalization due to knee OA was ~2-fold among those aged at least 40 years at baseline compared with those aged 30–39 years at baseline (Table 2). Controlling for age and gender, injury of the knee prior to hospitalization was the strongest predictor of hospitalization due to knee OA, followed by BMI. There was no association for either LTPA or smoking.

More than 20 years of cumulative exposure to physically heavy work or to standing or walking increased the risk of hospitalization due to knee OA (both by about 1.6-fold). The risk of hospitalization was increased already after 1 year of exposure to manual handling of heavy loads, while the association for cumulative exposure to kneeling or squatting was not linear. There was a linear association between composite cumulative workload and hospitalization due to knee OA.

In the fully adjusted model, predictors of hospitalization due to knee OA included age, gender, prior injury, BMI and composite cumulative workload (Table 3). The risk of hospitalization due to knee OA was attributed to prior injury, high BMI and intermediate to high composite cumulative workload by 37, 34 and 27%, respectively. These three factors accounted for 70% of hospitalized cases in total.

Risk Factors for First Hospitalization Due to Hip OA

There was a dose–response relationship between age and hospitalization due to hip OA. Controlling for age and gender, prior injury of the hip was the strongest predictor of hospitalization due hip OA (Table 2). The risk of hospitalization was similarly high among overweight and obese compared with those with normal weight (hazard ratio = 3.86, 95% CI: 1.99, 7.48; and hazard ratio = 4.46, 95% CI: 2.21, 8.99, respectively). Among the physical exposures, a borderline increase in the risk of hospitalization due to hip OA was observed for those with 1–10 years of exposure to kneeling or squatting only. No associations were seen for LTPA or smoking.

In the fully adjusted model, predictors of hospitalization due to hip OA included age, prior injury and BMI (Table 3). Most of the hospitalized cases (61%) were attributed to high BMI. Only 6% of hospitalizations due to hip OA were attributed to prior injury of the hip.

Stratified Analysis According to Age at the End of Follow-up

The vast majority of the first hospitalizations due to knee OA (97.9%) occurred at the age of 40–69 years, while most of the first hospitalizations due to hip OA (92%) occurred after the age of 50 years (Supplementary Table S2, available at Rheumatology online). We repeated the analyses in two strata according to age at the end of follow-up. Among persons aged ≤60 years at the end of follow-up, in total 75% of hospitalizations due to knee OA were attributed to prior injury, high BMI and intermediate to high composite cumulative workload (PAFs 34, 45 and 32%, respectively) (Table 4). In the same age group, 68 and 24% of hospitalizations due to hip OA were attributed to high BMI and intermediate to high composite cumulative workload, respectively (overall PAF 76%). Among persons >60 years of age, in total 79% of hospitalizations due to knee OA were attributed to prior injury, high BMI and intermediate to high composite cumulative workload (PAFs 46, 52 and 32%, respectively) and 73% of hospitalizations due to hip OA were attributed to high BMI.

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