Validity and reliability of the Urdu version of the 5D itching scale to assess pruritus among patients with chronic kidney disease in Pakistan

Chronic kidney disease (CKD) has become a major public health issue worldwide in the past few years, owing to its increased prevalence and incidence [1, 2]. In 2013, CKD was directly linked as the cause of approximately 956,200 deaths worldwide, 134.6% more than that recorded in 1990 [3]. It is due to this reason that CKD has increased in ranking in terms of highest mortality rate, from 27th in 2010 [4] to 19th in 2013 [5]. The incidence of chronic kidney disease is reported to be higher in South Asian populations as compared to European populations [6, 7]. In Pakistan, CKD is on the rise, with multiple factors being cited, for instance poor availability of health care, a faulty primary health care system, inadequate health education, insufficient government financial support, and high rates of diabetes and hypertension [8]. In addition, the lack of a national-level department in Pakistan for registering kidney diseases makes it next to impossible to assess CKD cases, the no of patients on dialysis, mortality rates, and subsequently, how funds should be allocate [8]. A recent study published in 2014 regarding the prevalence of chronic kidney disease in Pakistan suggested a prevalence rate of 12.5% [9].

Pruritus adds to the complications of patients with CKD. It is well recognized as a common complication in patients with chronic renal failure [10‐12]. Pruritus is an unpleasant sensation, accompanied by a desire to scratch oneself at the affected areas in order to obtain relief [13]. Pruritus is not only graded as the most common, but also incapacitating complication that has major long-standing effects on the patient’s quality of life, and prevalent in patients with end stage renal disease (ESRD) undergoing peritoneal dialysis (PD) and Hemodialysis (HD) [14‐18]. At any point in time almost every patient undergoing dialysis suffers from pruritus, irrespective of the severity of it [19], and has been reported in 22% to 84% of patients in ESRD who have undergone hemodialysis [15‐18, 20‐23]. According to another study, there is a higher percentage of pruritus in patients with stage 3 (18%), stage 4 (26%) and stage 5 (42%) CKD, while the incidence patients with stage 5 CKD stage 5 on maintenance hemodialysis: was reported to be 58% [24]. Pruritus can be generalized, which is less frequently seen, and affects the back, face, and fistula arm [25]. However it can be localized to the back, abdomen, or at the head [26]. CKD-associated pruritus is linked to poor quality of life, sleep disturbance, and depression [27, 28]. Severe pruritus can also lead to depression [25], and may result in the development of skin excoriations due to excessive scratching [29]. There is also an increased risk of suicidal thoughts [30], and a higher risk of mortality [16, 25].

It has been found that the treatment of pruritus is affected by two factors: whether it is localized or generalized; and the severity. For measurement of the former, several tools can be used, such as the Visual Analogue Scale (VAS) [16], Eppendorf Itch Questionnaire (EIQ) [31], Skindex-10 [20], or itch MOS (itch medical outcome study) [20]. There is currently no universal scale adopted to measure CKD-associated pruritus’ prevalence, severity, and impact on quality of life. Indeed a universal scale should have the ability to evaluate the severity, degree, duration, and impact on quality of life in a heterogeneous patient population. In Pakistan the prevalence of chronic kidney diseases and CKD associated pruritus reported is 64.64–77.7% [32, 33] and the 5D itch scale is not validated in Pakistan. As English is not understood and spoken by majority of Pakistani population and Urdu language is the national language so it is widely spoken in Pakistan.

Therefore, the aim of our study was to validate the Urdu version of the 5D itch scale among patients with chronic renal disease in Pakistan.

A validation study was performed from July to September 2016, at a tertiary health care setting in Peshawar Pakistan. To assess for discriminative validity of the 5D–IS, we recruited patients regardless of whether or not they had pruritus.

A total of 50 participants undergoing dialysis were recruited. Of these, 64% were males, while pruritus was reported by 70% of respondents (Table 1).

Pruritus is one of the most common symptoms observed in patients with chronic kidney disease undergoing dialysis. Previous studies have presented different prevalence rates of CKD-associated pruritus, ranging from 22% to 84% among patients undergoing dialysis [41‐43]. Our study found a prevalence rate of 70% in Pakistan, which is almost similar to previous studies in Pakistan which reported prevalence rates of 64% [44], 64.64% [33], and 77.7% [32]. The intensity of pruritus as reported in our study was mild (14%), moderate (50%), and severe (14%); differing from a previous study in Pakistan which reported different pattern of intensity mild (50%), moderate (28%), and severe (14%) [45]. The current study established that CKD-associated pruritus has a distressing impact, and contributes to lower quality of life. Important aspects related to quality of life affected by CKD-associated pruritus in this study were delay in falling asleep, and impaired ability to perform housework/errands. Similar finding were also found in other studies in which patients with moderate to extreme intensity of CKD-associated pruritus reported difficulty sleeping at night, feeling sleepy during the day, and nocturnal awakenings [46, 47]. The onset, duration, and the intensity of pruritus can change over time, and the itching is usually worse at night [25]. Pruritus may be episodic or constant, may be generalized or localized, and its intensity may vary from mild to severe [48]. Among patients with localized pruritus, the body parts most affected are the back, limbs, chest, and head; while about 20–50% of patient experience generalized pruritus [25]. However, our findings suggest that among the sixteen body parts listed in the Urdu version of the 5D itch scale, the following body parts i.e. thighs, buttocks, and abdomen, were the most effected; as reported by respondents.

The Visual analogue scale (VAS) is the most frequently used tool for quantification of pruritus. VAS is an adequate tool for assessing the severity of pruritus, however, it failed to address other aspects of pruritus like its relative impact on quality of life. Other tools recommended by the International Forum for the Study of Itch (IFSI) [49] for assessment of CKD-associated pruritus in patients undergoing dialysis are the itch medical outcome study [20], Skindex-10 [20] and brief itchy inventory [20]. However, these tools lack a comprehensive assessment of its psychometric properties. In order to address the short comings of these tools, a multidimensional tool i.e. the 5D itch tool, a single page tool which was specifically designed for measuring itch/pruritus that is easy to complete, assesses the impact of itch on quality of life, and adequately detects changes over time [31].Indeed the 5D itch scale has the ability to evaluate the severity, degree, duration and impact on quality of life in domains such as sleep, leisure/social life, and house work. The internal consistency of the English version of the 5D itch scale was good i.e. Cronbach’s alpha = 0.734 [31]. However, the Cronbach’s alpha for the Urdu version was found to be higher (Cronbach’s alpha = 0.914 with significant intraclass correlation coefficient p < 0.001). In our study, the KMO value was 0.802 with Chi-Square value (χ2 = 297.704), and Bartlett’s test of sphericity was significant (df = 28, p < 0.001). The intraclass correlation coefficient (ICC) between the 5D itch scale test re-test was 0.939 (95% confidence interval 0.91–0.96), which is a highly significant correlation (p < 0.0001), while for the English version of the 5D itch scale the ICC obtained was 0.96 (95% confidence interval 0.92–0.98), which is also a highly significant correlation p < 0.0001 [31]. The overall Kappa value calculated is 0.742, which was also significant (p < 0.001). Also, the discriminative validity established no significant changes in test (baseline) and re-test results.

The results showed that the Urdu version of the 5D itch scale had good reliability and validity for evaluating pruritus among patients with chronic kidney disease in Pakistan. Therefore, for clinical studies and assessment of pruritus t in patients with chronic kidney disease, the Urdu version of the 5D itch scale is a suitable and brief tool that can be used.