Incidence of Autoimmune Diseases in 30,340 Danish Women With Polycystic Ovary Syndrome (PCOS) Compared to 151,520 Controls. A National Cohort Study
Authors' conclusion
The incidence rate of autoimmune disease was higher in women with PCOS compared to controls, before and after PCOS diagnosis, and this higher incidence was associated with lower socioeconomic status, comorbidity and higher BMI.
Study context
- Population
- Danish women with PCOS and age-matched controls; median age at PCOS diagnosis 29 years (IQR 23; 36)
- Participants
- 30,340 vs 151,520
- Exposure
- Women with PCOS vs age-matched controls
- PCOSn = 30,340
- Controlsn = 151,520reference
- Outcome
- Autoimmune disease (ICD10 diagnosis of autoimmune disease and/or medical treatment for T1D or thyroid disease)
Methodological detailsnational register-based, age-matched controls
- National register-based
- Age-matched controls
Main finding
As reported in the abstract
All autoimmune diseases
PCOS vs ControlsIncidence rate ratio (CI)P value
Before PCOS diagnosis (mean risk time 11.3 years)
1.52(1.45–1.59)
After PCOS diagnosis (mean follow-up 9.8 years)
1.50(1.44–1.57)
all p < 0.001Observational data: associations, not effects.
Further findings
| Outcome | IRR (CI) | P value | |
|---|---|---|---|
| T1DPCOSvs ControlsBefore PCOS diagnosis | 2.31 (2.06–2.59) | ||
| T1DPCOSvs ControlsAfter PCOS diagnosis | 3.49 (3.16–3.87) | all p < 0.001 | |
| Thyroid diseasePCOSvs ControlsBefore PCOS diagnosis | 1.72 (1.61–1.84) | P < 0.001 | |
| Thyroid diseasePCOSvs ControlsAfter PCOS diagnosis | 1.48 (1.40–1.57) | all p < 0.001 | |
| 0.20.5125Incidence rate ratio (log scale) |
Factors associated with higher autoimmune disease incidence in PCOS · before and after PCOS diagnosis
- Higher incidence related to foreign ethnicity, low family income, comorbidity, infertility and higher BMI
Original publication
Incidence of Autoimmune Diseases in 30,340 Danish Women With Polycystic Ovary Syndrome (PCOS) Compared to 151,520 Controls. A National Cohort Study. Clin Endocrinol (Oxf). Published 13 August 2025. doi:10.
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