Comparison of pre- and post-natal environmental exposures in United States versus Brazilian patients with juvenile dermatomyositis
Authors' conclusion
Earlier onset of symptoms, possibly related to early life environmental exposures, was observed in Brazilian patients. Their mothers lived and worked closer to factories and quarries, commuted to work by bus and were more exposed to dust and tobacco.
Study context
- Population
- Juvenile dermatomyositis (JDM) patients from 4 centres (3 U.S., 1 Brazil); exposures during pregnancy and after birth assessed by questionnaire4 centres
- Exposure
- US vs Brazilian JDM patients
- Outcome
- Differences in environmental exposures (occupational exposures, inhalable pollution sources near mother's home and work, tobacco/alcohol)
Methodological detailsmulticentre, questionnaire-based
- Multicentre
- Questionnaire-based
Main finding
As reported in the abstract
Environmental exposures
- Mother worked outside home during pregnancy, U.S. vs Brazil
- 65.2% vs. 41.2%; p=0.032
- Worked in offices, U.S. vs Brazil
- 51.2% vs. 14.3%; p=0.027
- Worked as teachers, Brazil vs U.S.
- 28.6% vs. 4.8%; p=0.029
- Commuted by subway, U.S. vs Brazil
- 68.3% vs. 7.1%; p≤0.01
- Commuted by bus, Brazil vs U.S.
- 64.3% vs. 14.6%; p=0.001
- Exposed to dust, Brazil vs U.S.
- 42.9% vs. 9.5%; p=0.01
- Exposed to tobacco, Brazil vs U.S.
- 50% vs. 23.1%; p=0.01
- Workplace close to factories and quarries, Brazil vs U.S.
- 35.7% vs. 9.1%; p=0.03
- Home close to factories and quarries, Brazil vs U.S.
- 50% vs. 10.6%; p≤0.01
- Birthplace close to factories and quarries, Brazil vs U.S.
- 32.3% vs. 8.6%; p=0.007
- Postnatal tobacco exposure from father's smoking, Brazil vs U.S.
- 26.5% vs. 6.2%; p=0.009
- Postnatal tobacco exposure from other household residents, Brazil vs U.S.
- 36.4% vs. 9.2%; p=0.002
Observational data: associations, not effects.
Further findings
| Outcome | U.S. | Brazil | P value |
|---|---|---|---|
| JDM age at onset (years) | mean 7.12 (SD ±4.02) years | mean 5.30 (SD ±2.52) | P = 0.004 |
Parts of this Brief are withheld: the automatic checks could not confirm them against the abstract.
Original publication
Comparison of pre- and post-natal environmental exposures in United States versus Brazilian patients with juvenile dermatomyositis. Clin Exp Rheumatol. Published 26 September 2025. doi:10.
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