#2153 Difelikefalin: a new solution against itching in CKD-aP patients

Abstract Background and Aims Chronic kidney disease-associated pruritus (CKD-aP) is one of the most common and burdensome symptom affecting patients with advanced chronic kidney disease, with an estimated prevalence of 53.3%. The clinical presentation is extremely variable, from minor lesions to true scratch injuries, and significantly affects the patient's quality of life (QoL), sleep quality and mood, as well as being associated with increased mortality. At present, high-quality evidence on which to base treatment is limited. Currently proposed first-line therapeutic options include optimization of dialysis treatment, emollient agents, UVB light, antihistamines, gabapentin and pregabalin. Recently difelikefalin, a k-opioid receptor agonist, has been the first Food and Drug Administration (FDA) approved drug for moderate-severe CKD-aP treatment. The aim of our study is to demonstrate the efficacy of this drug in relieving symptoms in CKD-aP patients. Method For this preliminary retrospective observational study, 19 patients (9 females, 10 males) with CKD-aP performing dialysis at our Dialysis Center were recruited. All of them had appropriate Kt/V values and had previously been treated with first-line medications. The other main demographic and clinical characteristics of our population, such as calcium-phosphate metabolism and inflammation's indexes, can be seen in Table 1. Our population underwent the Worst Itch Numeric Rating Scale (WI-NRS) by which the presence, intensity, and impact on sleep of this symptom were investigated. They also were subjected to questions that investigate their quality of life (SF-PCS12, SF-MCS12). All patients completed those questionnaires before starting Difelikefalin treatment (t0) and after one month of treatment (t1), 15 of them were evaluated also after three months (t3) and 10 patients, those who first started therapy, reached the assessment at six months (t6). Results Statistical analysis of our preliminary study shows very encouraging data regarding the efficacy of difelikefalin on CKD-aP and sleep quality. As shown in Table 2, we recorded a significant decrease (p value <.001, ƞ2 0.552) in the intensity of itching, most noticeable in the first month, confirming that the effect of this drug is evident and considerable already after four weeks. Our data also demonstrate a significant and lasting positive effect of difelikefalin on sleep quality (p value 0.006, ƞ2 0.592), as shown in Table 3. We found no significant data on the improvement in the QoL of the patients in the study, probably due to the difficulty in standardising this complex feature and due to the limited size of the statistical sample. Furthermore, it should be considered that 3 of the patients enrolled in the study had to discontinue the medication due to the onset of side effects such as diarrhea and headache. Conclusion The most influential limitation of this retrospective observational study is the small number of recruited patients, in addition to the fact that not all of them reached a 6-months treatment evaluation. Our aim is to complete the study by enrolling a larger number of patients from our Dialysis Centre and to monitor the effect of difelikefalin during a longer treatment period, in order to achieve a more accurate analysis and significative results applicable on a larger scale. As far as we can currently evaluate, this drug is significantly effective in reducing CKD-aP and thus in improving the quality of sleep.