A longitudinal study of uremic pruritus in hemodialysis patients

Abstract

Background and objectives: Although uremic pruritus (UP) is a highly prevalent complication of chronic kidney disease, it remains poorly characterized. There have been no longitudinal studies of natural history, and no health-related quality of life (HR-QOL) instruments have been developed for UP. The objectives of this study were to describe the natural history of UP, to compare rating scales of itching intensity, and to assess usefulness and validity of HR-QOL instruments for UP.

Design, setting, participants, & measurements: The intensity, severity, and effects of pathologic itching on HR-QOL were assessed prospectively in 103 patients with UP on chronic hemodialysis. Outcome measures were obtained at scheduled intervals over 3.5 months.

Results: Itching daily or nearly daily was reported by 84% of patients and had been ongoing for >1 year in 59%. In 83%, pruritus involved large, nondermatomal areas with striking bilateral symmetry. Two thirds of the patients were using medications such as antihistamines, steroids, and various emollients without satisfactory relief of itching. Statistically significant associations were found among itching intensity, severity, and HR-QOL measures in domains such as mood, social relations, and sleep. Among patients with moderate-to-severe UP, changes in itching intensity of 20% or greater were associated with significant reductions in HR-QOL measures.

Conclusions: This first longitudinal study of UP describes key features of UP and its effect on HR-QOL. The assessment instruments we have developed are easily used, are responsive to changes in UP intensity, and should facilitate clinical evaluation and research to meet the needs of afflicted patients.

Figure 1.

Skindex-10. Patients filled one of seven bubbles (“0 [never bothered], 1, 2, 3, 4, 5, and 6 [always bothered]”) for each of the questions. The total score was the sum of the numeric value of each answered question. The domain scores were sums of the following: disease domain (questions 1 to 3), mood/emotional distress domain (questions 4 to 6), and social functioning domain (questions 7 to 10).

Figure 2.

Brief Itching Inventory. Patients filled 1 of 11 bubbles (“0 [itch does not interfere)] 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 [itch completely interferes]”) for each of the questions above. The total score was the sum of the numeric value of each answered question. The body diagram was not quantified.

Figure 3.

Itch MOS (of sleep). For most questions, patients circled one of six numbers ranging from “1” (“all of the time”) to “6” (“none of the time”), indicating the frequency of various aspects of pruritus-related sleep disruption over the preceding week. Patients also estimated the average amount of sleep per night during the past week.

Figure 4.

Patient self-categorization of pruritus disease severity. Patients selected one of three patient profiles that most closely resembled them.

Figure 5.

Over 12 weeks of follow-up, itch intensity fluctuated and appeared to be cyclical in some patients, although rarely normalizing if the baseline VAS was >40 mm. SCR, screening; BL, baseline; WK, week.

Figure 6.

Spatial patterns of uremic pruritus. (A) Representative body diagrams from 3 subjects depicting pruritus-affected areas. (B) Pruritus distribution in a single patient at baseline and at week 14 in the study.

Figure 7.

Quality of life decrements with incremental increases in pruritus intensity (VAS). Linear relationship between 10-mm incremental increases in the visual analogue scale score between 30 and 80 mm and quality of life decrements on the Skindex-10 and Brief Itching Inventory.