Background/Purpose: GPA is a rare condition of unknown etiology. Prominent involvement of the upper and lower respiratory tracts suggests that inhaled antigens may trigger systemic immunopathogenic responses. Although no definite inhaled environmental factor has been identified farming and solvent exposure have been reported to be associated with GPA in Northern hemisphere studies. A latitudinal gradient has been observed in both Northern and Southern hemispheres with higher rates of disease in those areas closest to the North and South Poles. The aim of this study was to determine any environmental risk factors for GPA in Canterbury New Zealand (latitude 43o-44oS), with a particular focus on inhaled antigens.
Methods: A case-controlled study was undertaken. All GPA cases fulfilled ACR or CHCC criteria. Each case was age ± 10yrs and gender matched with four controls (2 osteoarthritis or fracture and 2 asthma or emphysema). A structured questionnaire to assess potential environmental agents was administered. Data was analyzed using conditional logistic regression to allow for the individual matching of cases and controls.
Results:
49 cases and 196 controls were recruited. 53% were male and 97.5% were New Zealand European. The mean ± SD age of the cases was 64.9 ± 12.4yrs and controls 59.5 ± 14.6yrs. In the 2 years prior to the first symptoms attributable to GPA 14.3% of cases and 18.6% of controls lived in a rural environment (p=0.48). Place of birth within New Zealand (whether North Island or South Island) had no influence on risk (p=0.7).
Any reported exposure to dust (specifically silicon and grain dust) increased the risk of GPA, OR 3.6 (1.5 – 8.3, p=0.003). GPA was associated with a higher intensity of exposure to silica (p<0.001), metals (p=0.003) and solvents (p<0.001).
Occupation as a farm worker was associated with GPA OR 3.43 (1.5 -7.5, p=0.002). In the year prior to the first symptoms attributable to GPA cases were significantly more likely to have lived on, worked on or visited a farm than controls OR 2.7 (1.3-5.9; p=0.009). There was no significant relationship between exposure to crops (OR 1.7; 0.8-3.6; p=0.16). However exposure to livestock was associated with an increase risk (OR 2.3; 1.1-5.0; p=0.02), specifically exposure to sheep (OR3.6; 1.6-7.7; p=0.001). GPA was also associated with more time spent in the garden (Cases 22.7 ± 4.1 hrs/month vs. controls 13.2 ± 2.0 hrs/month p=0.04). Specific gardening activities were associated with increased risk including digging (OR 3.2; 1.4-7.0; p=0.003), mowing (OR 2.7; 1.3-5.8; p=0.008) and planting (OR 2.6; 1.2-5.5; p=0.013).
Conclusion: Previous studies have identified a latitudinal gradient and a peak in GPA disease onset in the winter months. We have shown activities associated with exposure to inhaled antigens, in particular those related to farming or gardening activities may increase the risk of GPA. We have replicated findings from northern hemisphere studies identifying dust and solvent exposure as well as farm exposure as risk factors for the development of GPA.
Disclosure:
L. K. Stamp,
Astra Zenec,
5,
Abbvie,
9,
PHARMAC,
6;
P. T. Chapman,
None;
R. A. Watts,
None;
C. Frampton,
None;
J. L. O’Donnell,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/environmental-risk-factors-for-granulomatous-polyangiitis-gpa-southern-hemisphere-similar-to-northern-hemisphere/