Disparities Between Rural and Urban Communities: Response to 18 Months of Diet and Exercise Versus Control for Knee Osteoarthritis and Overweight or Obesity

Abstract

Objective: The study objective was to determine whether the clinical response of older adults with knee osteoarthritis and overweight or obesity to 18 months of diet and exercise (D + E) or attention control (C) interventions differed between participants from rural versus urban communities.

Methods: Participants were 823 older adults (mean age, 64.6 years; 77% women) with knee osteoarthritis and overweight or obesity who resided in rural (n = 410) and urban (n = 413) counties in North Carolina. All were enrolled in the Weight Loss and Exercise for Communities with Arthritis in North Carolina clinical trial that randomly assigned participants to either 18 months of D + E or C interventions. General linear models were used to examine differences in clinical outcomes between rural and urban groups after adjusting for covariates.

Results: The rural group had significant differences (P < 0.05) at baseline in clinical outcomes, education, comorbidities, medication use, and income compared with the urban dwellers. After adjusting for baseline differences, the group (rural or urban) by treatment (D + E or C) interactions for Western Ontario McMasters Universities Osteoarthritis Index (WOMAC) pain (rural: D + E - C = -0.63, 95% confidence interval [CI] -1.31 to 0.06; urban: D + E - C= -0.29, 95% CI -0.99 to 0.41; P = 0.50) and WOMAC function (rural: D + E - C = -4.60, 95% CI -6.89 to -2.31; urban: D + E - C = -1.38, 95% CI -3.73 to 0.94; P = 0.054) indicated that the groups responded similarly to the interventions.

Conclusion: Among participants with knee osteoarthritis and overweight or obesity, D + E compared to C led to similar pain outcomes in rural and urban dwellers that favored D + E. The possibility that there may be greater differential efficacy in functional outcomes among rural participants needs further study.

Figure 1

Box plots are shown in which the middle line represents the median value, the X the mean value, and the box represents the interquartile range. Whiskers extend to the most extreme observed values within the 1.5 times the interquartile range of the nearer quartile, and dots represent observed values outside the range. WOMAC, Western Ontario McMasters Universities Osteoarthritis Index (range 0 [no pain] to 20 [severe pain]).

Figure 2

(A) Pairwise comparisons (95% confidence interval) between D + E and C in WOMAC pain for rural and urban communities. Negative values indicate that the D + E group had less pain than the C group. Positive values indicate that the C group had less pain than the D + E group. (B) Pairwise comparisons (95% confidence interval) between D + E and C in function for rural and urban communities. Negative values indicate that the D + E group had better function than the C group. Positive values indicate that the C group had better function than the D + E group. BMI, body mass index; C, attention control; D, diet; E, exercise; WOMAC, Western Ontario McMasters Universities Osteoarthritis Index.

Figure 3

Pairwise comparisons (95% confidence interval) between D + E and C in BMI for rural and urban communities. Negative values indicate that the D + E group reduced BMI more than the C group. Positive values indicate that the C group reduced BMI more than the D + E group. BMI, body mass index; C, attention control; D, diet; E, exercise.