A total of 12,181 studies were identified through the initial search. Following deduplication, 2499 articles were excluded. Subsequent title and abstract screening were performed on 9685 studies, with 9599 being deemed incongruent with the eligibility criteria and subsequently excluded. The remaining 86 studies underwent a full-text review, and 29 studies were included in the review. Figure 1 outlines the article selection process through a PRISMA chart.

PRISMA flowchart illustrating the study selection process

The included studies comprised 18 cross-sectional studies [26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43], 10 cohort studies [2, 3, 44,45,46,47,48,49,50,51], and 1 case–control study [52]. They were primarily conducted in Germany (n = 7) [3, 41, 42, 44, 46, 49, 50], followed by the United States (n = 6) [3, 38, 47,48,49,50], France (n = 5) [3, 38, 48,49,50], and Italy (n = 4) [3, 49,50,51]. The studies included a cumulative patient population of 147,174 individuals with CKD. Most studies focused on patients receiving dialysis, with 27 studies assessing the outcomes in HD patients [2, 3, 26,27,28,29,30,31,32,33,34,35,36,37, 39,40,41,42,43,44,45,46,47, 49,50,51,52], and only three studies investigating the outcomes in patients on both haemodialysis (HD) and peritoneal dialysis (PD) [40, 47, 51]. However, a much smaller number of studies included patients in either the pre-dialysis stage (n = 2) [38, 48] or both the dialysis and pre-dialysis stages (n = 1) [26]. Notably, all three studies included patients with advanced CKD on the conservative (non-dialysis) pathway. Among dialysis patients, the majority were undergoing HD (n = 67,479), while a small proportion were either on PD (n = 387) or in the pre-dialysis stage (n = 8296). One study included a total of 71,012 patients on dialysis but did not provide a breakdown between HD and PD [47].

The systematic review included a diverse range of studies employing various instruments to assess different aspects of patient-centred outcomes and overall well-being. Itch and its severity were comprehensively evaluated through different instruments, including the Visual Analogue Scale (n = 6) [2, 26, 39, 44, 46, 51], 5-D Itch Scale (n = 10) [27,28,29, 31,32,33,34,35,36, 43], Numerical Rating Scale (n = 1) [52], and 12-point Pruritus Severity Scale (n = 1) [37].

Using the range of risk JBI resources for assessing risk of bias of cross-sectional, cohort, and case–control studies, 5 studies were rated as high quality [30, 40, 48, 50, 51], while 24 studies were categorised as moderate quality [2, 3, 26,27,