Background/Purpose: Past studies have revealed disparity in the clinical significance of thrombocytopenia in systemic lupus erythematosus (SLE), ranging from a benign and incidental finding in some to a life-threatening manifestation, associated with severe disease and a high mortality rate in others.   Some patients evolve to a state of chronic isolated thrombocytopenia (CIT), the clinical significance of which is unknown.  It is thus unclear whether this isolated finding warrants prompt, reactive therapy, or whether these patients may be monitored, free from immunosuppressive therapies and their associated toxicities, without risk of worsening disease activity.  Thus the purpose of this study was to investigate the clinical correlates of CIT in a large cohort of SLE patients. 

Methods: Patients with CIT were identified from the Lupus Clinic database.  CIT was defined as at least two consecutive visits, ≤18 months apart, with SLE Disease Activity Index 2000 (SLEDAI-2K) score of 1 from platelets < 100, irrespective of pharmacotherapy.  Any divergence from this score ended the thrombocytopenic period.  Descriptive statistics were used.

Results: 16/1678 (1%) patients had CIT, occurring over 42 discrete episodes, and spanning 147 visits.  The mean duration of a thrombocytopenic episode was 10.9 months, and the mean cumulative duration of isolated thrombocytopenia per patient was 28.6 months.  Mean time to first CIT episode from clinic entry was 8.6 years (range 4 months – 31 years).  Platelet counts during these periods ranged from 15 – 99, and were associated with antiphospholipid antibody positivity in 6/16 (37.5%).  Fifteen patients (93.8%) were known to have thrombocytopenia as an SLE manifestation, associated with other signs/symptom of activity, earlier in their disease course; in the remaining patient it correlated with the introduction of an herbal remedy.  There were no clinically significant episodes of bleeding in any of the patients over the visits studied, but critically low counts (≤20) were managed by increasing immunosuppression. Thrombocytopenia was associated with pregnancy in 3/42 (7.1%) of the episodes.  Eleven patients (68.8%) were taking steroids at low doses, and six patients (37.5%) each were taking antimalarials or immunosuppressives during the CIT episodes.  At times, these therapies overlapped.  Four patients (25%) required none of these therapies for the duration of their CIT episodes.  Prior to or after a CIT episode, patients were serologically and clinically quiescence in 14/78 (17.9%) instances, had active serology with or without thrombocytopenia in 34/78 (43.6%) instances, and were clinically active in 27/78 (34.6%) instances; there were more than 18 months between visits in three instances. 

Conclusion: CIT is a rare event that can occur anytime in the SLE disease course and is usually associated with treatment with low dose steroids and/or immunosuppressives.  Patients with this manifestation require close clinical monitoring and cannot be considered to be in remission.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-correlates-of-chronic-isolated-thrombocytopenia-in-patients-with-systemic-lupus-erythematosus/