Background: Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage according to the International Association for the Study of Pain.

Aim: To estimate distinguishing features of the pain in patients with blood disorders.

Patients and Methods: The prospective exploratory study was conducted in the National Research Center for Hematology, Moscow from 11/2015 to 01/2021. In total, 40 patients (pts) with blood disorders who had a difficult-to-control pain syndrome were included in the study. There were 21 men (median age of 41.5, IQR 35.0-56.3 years) and 19 women (median age of 40, IQR 34.3-56.0 years). The pain types were determined according to clinical symptoms and the use of special questionnaires (i.e., the Douleur Neuropathique 4 Questions questionnaire for neuropathic pain). Pressure algometry was used to assess pain tolerance of the non-dominant hand by evaluating the pressure pain threshold (PPT, kg/cm 2), which is the minimum pressure required to induce pain.

Results: Four types of pain were identified: neuropathic in 9 pts (22.5%), nociceptive in 9 pts (22.5%), their mix (summing up to a half of the total number of cases ‒ 52.5%, 21 pts) and dysfunctional pain in only 1 patient (2.5%). The distribution based on the pain types was uneven (Kolmogorov test, p = 0.05). The different pain types were related with various distributions of blood disorders: lymphoid tumor (44.5%), myeloid tumor (33.3%) and not tumor (22.2%) (associated with neuropathic pain) and myeloid tumor (88.9%) and not tumor (11.1%) (associated with nociceptive pain) (Figs. 1 and 2) . The tolerance of neuropathic and nociceptive pain types turned out to be significantly different (PPT medians with 95% CI): 2.2 kg/cm 2 (1.6-3.1) vs. 4.6 kg/cm 2 (3.9-5.5), respectively, and (found in ROC-analysis) the cut-off was 3.2 kg/cm 2,AUC (the area under ROC curve) 96.3%, sensitivity and specificity 88.8% (Fig. 3 and 4). PPT cut-off points, that shares the mixed pain (median 2.7 kg/cm 2, 95 CI 1.9-3.6) on the neuropathic and nociceptive pain are: 3.2 kg/cm 2 (AUC 67.0%) and 3.8 kg/cm 2 (AUC 86.7%), respectively. Several measurements of PPT (with taking into account the cut-off) in patient, suffering from pain, can help identify with a high probability his type of pain, and accordingly (indirectly), his blood type disorder.

Conclusions: Measuring PPT in a pts with blood disorders allows to identify the type of pain (neuropathic, nociceptive, or combined), which can serve as an additional source of information for accurate diagnosis and treatment.

Figure 1
Figure 1.
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Disclosures

No relevant conflicts of interest to declare.

© 2021 by The American Society of Hematology
2021
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