Oral and Poster Presentation 45th Annual ARA NSW-ACT Branch Meeting 2023

Association of hip pain exacerbations with air pollutants (#20)

Xiaoqian Liu 1 2 3 , David Hunter 1 2 3
  1. Royal North Shore Hospital, St Leonards, NSW, Australia
  2. Rheumatology Department, Northern clinical school, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
  3. sydney musculoskeletal flagship, Sydney, NSW, Australia

Objective

The objective was to evaluate the association of air pollutants with the risk of pain exacerbations in people with symptomatic hip osteoarthritis (OA).

Methods

We conducted a time-stratified case-crossover study among patients with symptomatic hip OA who experienced pain exacerbation using data from our previously published study. Pain exacerbation was defined as an increase of two points from baseline using an 11-point numeric rating pain scale (0-10). The day on which the hip pain flare occurred was used as the index day to anchor the 3-day hazard period. The control period was matched to the same day of the week of the hazard period within the same block. Air pollution data were obtained for both hazard and control periods from the publicly available meteorological database of the Australian Bureau of Meteorology. Each air pollutant indicator was classified into five categories (i.e., good, fair, poor, very poor, and extremely poor) reflecting the air quality categories used to summarize air quality measurements. The association of each air pollutant factor with the risk of pain exacerbation was assessed using conditional logistic regression. Odds ratios were reported as the effect measure along with corresponding 95% confidence intervals.

Results

A total of 127 participants who met the inclusion criteria and reported at least one episode of pain exacerbation were included in the analysis. The average number of pain exacerbation episodes per person was 2.43 (SD = 1.84, range = 1 to 10). The baseline mildest pain level was reported as 2.5 ± 2.0 out of 10, while the worst pain level was reported as 8.1 ± 1.7 out of 10.

The analysis did not reveal any statistically significant associations between air pollutant factors (PM2.5, PM10, NO2, SO2, O3, CO) and the risk of pain exacerbations (table 1&2), regardless of whether the analysis was based on the good/not-good classification or the original good to the extremely poor classification of air pollutants. Furthermore, the variation in air pollutant levels over 72 hours did not exhibit a statistically significant effect on the likelihood of pain exacerbations.

Conclusion

Overall, the findings suggest no association between air pollutants and hip pain exacerbations in people with symptomatic hip osteoarthritis. However, the findings need to be interpreted with caution because of limited number of people in the poor to very poor categories meaning less variance in the data. Further larger studies are needed to ascertain the findings.

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