Health Related Quality of Life in Patients with Primary ITP Compared with Population Norms: A Multicenter Retrospective Analysis of Data from Norwegian ITP Registry

Introduction: Immune thrombocytopenia (ITP) is characterized by thrombocytopenia and varying grades of bleeding manifestations. Many patients develop a fear of bleeding, which can impact their health-related quality of life (HRQoL). In addition, often necessary lifestyle adjustments as well as treatment-related side effects may further reduce HRQoL.

Aims: to estimate HRQoL in adult patients diagnosed with ITP and to compare their HRQoL to that of the general population using the EuroQol-5 Dimensions-3 Levels (EQ-5D-3L) questionnaire.

Methods: Data from the Norwegian ITP (NOR-ITP) Registry was used. Adult ITP patients registered in NOR-ITP from Dec 2016 to May 2023 were included in this study. Patients included in NOR-ITP complete the EQ-5D-3L questionnaire, when included in the registry and then annually as part of their scheduled follow-up. In patients who had completed several EQ-5D-3L questionnaires, the most recent one was used. The age-adjusted Norwegian EQ-5D-3L populations norms were used as reference values for Index and VAS scores. Missing data were replaced using multiple imputation.

Results: Median (IQR) age of 247 patients was 57 years (34); M:F ratio = 1:1.5. ITP was newly diagnosed in 18 (7%), persistent in 14 (6%), and chronic in 215 (87%) patients. Platelet count was >50*10 ⁹/L in 166 (67%) patients, between 31 and 50*10 ⁹/L in 15 (6%), and < 30*10 ⁹/L in 18 (7%), unknown for 19% (48). Thirty-nine (16%) patients were never treated for ITP, 80 (32%) patients had remission induced by glucocorticoids +/- IVIGs, and 128 (52%) were treated with second-line agents. Ongoing treatment was an immunosuppressive agent (i.e. glucocorticoids +/- IVIGs, rituximab (received during the last 3 months), azathioprine, cyclosporine-A, mycophenolate mofetil) in 43 (17%) patients, a thrombopoietin receptor agonist in 42 (17%) patients, while 162 (66%) were off-ttraetment. Median time from diagnosis of ITP to most recent EQ-5D questionnaire was 4 (10) years. Figure1a displays the frequency of reported problems (levels 2 and 3) in ITP patients compared to the population norms. ITP patients reported significantly more problems in 4 out of 5 domains. EQ-5D index score was significantly lower in ITP patients compared to the general population [Mean (SD) = 0.790 (0.23) vs 0.830 ([0.041); p-value 0.007]. Likewise, we found VAS to be significantly lower in ITP patients compared to the general population [Mean (SD) = 70.82 (21.09) vs 77.32 (5.554); p-value 0.0001). Within the ITP cohort, we found significantly lower VAS scores in ITP patients receiving ongoing treatment compared to those off treatment (p-value 0.01), as shown in figure1b. However, no significant difference was found concerning Index scores when comparing patients with ongoing to off-treatment. Comparing index scores and VAS according to platelet count category (<30; 31-50; >50*109/L) and the phase of ITP did not reveal any significant differences.

Conclusion: This study is the first to evaluate HR-QoL using EQ-5D in a well-characterized cohort of patients with ITP. In line with existing evidence, using other HRQoL instruments, we found significantly reduced HRQoL in ITP patients compared to the general population. ITP patients receiving ongoing treatment had worse HRQoL compared to those off-treatment. Limitations of this study are the the long time period between diagnosis and completing the questionnaire, the observational and retrospective study design, and the lack of predictors for HRQoL.