The age-risk relationship of haematologic malignancies in female patients with systemic lupus erythematosus: a nationwide retrospective cohort study.

BACKGROUND: The risks of haematologic malignancies in female patients with systemic lupus erythematosus (SLE) have been observed to be higher in young age groups than in old age groups. However, the age-risk relationship between haematologic malignancies and SLE is poorly defined. DESIGN AND METHODS: A retrospective cohort study was conducted nationwide with newly diagnosed SLE female patients during the period of 1997 to 2001 using the database acquired from the Taiwan National Health Research Institute. Each patient in the study was randomly frequency matched with five SLE-free people based on age. The subsequent developments of haematologic malignancies were observed until the date haematologic cancer was diagnosed or December 2008. The age-adjusted standardized incidence ratios (SIRs), the incidence per 1000 person-years, the follow-up duration to the diagnosis of haematologic malignancies and the cumulative hazard rates of haematologic malignancies between SLE and controls were analysed. RESULTS: A total of 35 lymphoid and 14 myeloid malignancies were observed among 9349 female SLE patients. Further, significantly higher incidences of both lymphoid and myeloid malignancies were found in SLE patients (SIR: 3.30, 95% confidence interval (CI) = 2.20-4.93 and SIR: 2.86, 95% CI = 1.49-5.09). Also, two peaks of risk ratios for lymphoid malignancies were found in patients aged 21-30 years and 41-50 years. It was observed that the follow-up duration for haematologic malignancies was significantly shorter in SLE patients than in controls (73.21 vs. 105.25 months, respectively). In addition, higher cumulative hazard rates in both lymphoid and myeloid malignancies were found in SLE patients (p < 0.0001). CONCLUSION: Female SLE patients have a higher incidence of haematologic malignancy in different age groups, and with shorter incubating time than SLE-free people.