The Contribution of Age and Obesity to the Number of Painful Joint Sites in Individuals Reporting Osteoarthritis

A Population-Based Study

Elizabeth M. Badley; Jessica M. Wilfong; Calvin Yip; Dov B. Millstone; Anthony V. Perruccio

Disclosures

Rheumatology. 2020;59(11):3350-3357. 

In This Article

Results

Table 1 shows the distribution of characteristics of the sample. The majority of people reporting OA were women, over half were <65 years (56%), and two-thirds were overweight or obese. A fifth reported painful joint symptoms for ≤5 years, and three-quarters had at least one other chronic condition. Only 16% of respondents with OA reported pain at only one joint site, while 84% reported pain at two or more sites, and 45% at four or more sites. The reported painful joint sites in descending order of frequency were the knee (62.0%), hand (52.1%), back (51.6%), hip (43.7%), shoulder (38.1%), neck (34.1%), foot (27.2%), wrist (26.1%), ankle (23.2%) and elbow (17.3%).

Table 2 provides the distribution of painful joint site count categories and mean number of painful sites by sample characteristics. Women reported more painful joint sites than men. There were no clear trends in the number of painful joint sites by age, nor in the distribution of joint sites by education, smoking status or BMI. The proportion of respondents with 4+ joint sites increased with comorbidity count and symptom duration. The overall mean number of painful joint sites in the sample was 3.8. While mean painful joint site counts varied somewhat across characteristics of the sample, all were within a limited range of 3.1–4.5.

Results from the zero-truncated negative binomial regression model are presented in Table 3. Age, education, smoking status and BMI were not associated with the number of painful joint sites. Being female was significantly associated with a higher number of painful joint sites, as was having more comorbidities and a longer symptom duration. However, as can been seen from Figure 2, which shows the mean number of painful joint sites by age and symptom duration, there was only a slight increase in the number of painful joint sites with increasing duration. The mean number of painful sites increased by only 1.4 from a mean of 3.1 sites for the shortest symptom duration category (0–5 years) to 4.5 for the longest symptom duration category (20+ years). The number of painful joint sites did not show any consistent increase with age within each duration category.

Figure 2.

Mean painful joint sites by age and symptom duration: 2009 SLCDC-A OA sample (n = 1614)
aBased on 95% CIs (given in Table 1) there is a significant difference in the mean number of painful joint sites for the longest duration (20+ years) with each other duration period. There is no difference between the adjacent categories 0–5 and 6–10 years, and 6–10 and 11–19 years, but the difference in mean count between 0–5 and 11–19 years is significant.

The overall findings from our sensitivity analyses using the SLCDC-A sample were unchanged from the main findings. The findings from our parallel analyses in the clinical sample scheduled for joint replacement surgery were also consistent with our main findings (Table 4): neither age nor BMI was associated with the number of painful joint sites. Further information, including the characteristics of the sample (Supplementary Table S1, available at Rheumatology online) and the characteristics of the sample by number of painful joint sites and mean painful joint site count (Supplementary Table S2, available at Rheumatology online) is given in the supplementary material.

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