We conducted an observational and retrospective study to answer the two questions of whether fatigue can predict a thrombocytopenic episode in ITP and whether improvement in fatigue can predict response to treatment.
Patients were selected from the registry of patients who attended the haematology consultation at our centre during a two-year period (2010 and 2011), affected by ITP and with at least one ITP relapse episode with a platelet count below 60 x 109/l. We identified a total of 96 patients, but 14 had to be excluded for various reasons (were dead, unable to answer questions or could not be located). In total, 82 patients were included.
Biological and clinical data for each patient were collected from the electronic medical record using a pre-designed form. Data collected included age, sex, number of exacerbations, basal platelet count, basal haemoglobin (Hb) level, minimum platelet count and Hb level at each exacerbation, treatment and response. Responses to treatment were defined as: complete response (CR): platelet count ≥ 100 x 109/l and no bleeding; response (R): platelet count range 30-100 x 109/l and at least a 2-fold increase in baseline count with no bleeding; and non-response (NR) as platelet count < 30 x 109/l or less than a doubling of baseline platelet count or bleeding, according to guidelines12.
A 7-item survey was administered to all patients, the second of which was a visual analogue scale for fatigue (VAS-F, Figure 1). The questions were as follows:
1. Are there any symptoms that you associate with the decrease in platelet count?
-If YES → which ones?
-If NO → did you feel unusually tired before the decrease in platelet count?
2. On this scale (VAS-F), where 0 means no fatigue (no tiredness), 5 means moderately tired and 10 means extremely tired (extreme tiredness), where would you be?
3. Do you think that fatigue could predict the subsequent drop in platelets?
4. How many days did you feel tired before your doctor confirmed the drop in platelets?
5. Did the symptoms go away with treatment?
6. Do you think you could have predicted the increase in your platelet count by the improvement in your symptoms?
7. How many days did you feel better before you noticed the increase in your platelet count?
Figure 1. Visual analogue scale for fatigue (VAS-F)
Statistical analysis
Continuous variables are summarized with mean and range while categorical variables are summarized by number of patients and percentage. Qualitative data were compared with the Chi-squared test, using Fisher’s exact test when necessary. Quantitative variables were evaluated for normal distribution by Kolmogorov Smirnov test and then were compared by using the t-Student test or the Mann-Whitney U test. To evaluate the relationship between two quantitative variables, the Pearson correlation test was used when the variables had a normal distribution or the Spearman test when they did not. A p value < 0,05 indicated statistical significance. All statistical analyses were performed using IBM SPSS Statistics software (version 21.0).
The study was designed and conducted in accordance with the Declaration of Helsinki. It was approved by the local Ethics Committee and informed consent was obtained from all the patients who were included in the study.