Lupus & antiphospholipid syndrome
Prevalence and prognostic value of activated protein C resistance and anti–protein C antibodies in patients with aPLs: an APS ACTION Registry study
Authors' conclusion
A high prevalence of APCr was seen across all aPL-positive patients, strongly associated with high-avidity anti-PCs.
Study context
- Population
- Patients persistently positive for aPLs with/without APS, APS ACTION Registry370 patients and 51 healthy controls
- Participants
- 77 / 43 / 132 / 87 / 31 / 51
- Exposure
- aPL-positive patients by clinical phenotype vs healthy controls
- aPL-onlyn = 77
- Obstetric APS (OAPS)n = 43
- Venous thromboembolism (VTE)n = 132
- Arterial thrombosis (AT)n = 87
- VTE + ATn = 31
- Healthy controlsn = 51reference
- Outcome
- Prevalence of APCr and anti-PCs, associations with aPL profile and clinical phenotypes
- Follow-up
- Baseline
Methodological detailsAPS ACTION Registry study, prospective follow-up, healthy controls
- APS ACTION Registry study
- Prospective follow-up
- Healthy controls
Main finding
As reported in the abstract
Anti-PCs present in patients
42%
Observational data: associations, not effects.
Further findings
| Outcome | HR (95% CI) | P value | |
|---|---|---|---|
| Thrombotic events in non-anticoagulated patients (subgroup)APCrvs Without APCr | 4.5 (0.8–25.9) | P = 0.14 | |
| 0.050.21520Hazard ratio (log scale) |
- New thrombosis during prospective follow-up · median 8.3 years — New thrombosis · APCr or anti-PCs vs Without APCr or anti-PCs · similar incidences
- 25/283 (8.8%) · P > 0.60
- New thrombosis during prospective follow-up: 283 patients followed
Original publication
Prevalence and prognostic value of activated protein C resistance and anti–protein C antibodies in patients with aPLs: an APS ACTION Registry study. Rheumatology (Oxford). Published 13 June 2026. doi:10.
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