Design

This study is part of a larger randomised controlled trial to assess the effectiveness of a CKD nurse-led self-management support programme (CKD-NLSM) on kidney disease knowledge, CKD self-management, self-efficacy and quality of life among patients with CKD stages 3–4 [22]. First, forward and backward translations were conducted by a panel of experts who reviewed the translations and conducted cultural adaptation. The MCKD-SM was subjected to psychometric assessment.

Phase 1: Translation and cultural adaptation processForward translation and the expert panel

Approval to use the CKD-SM was granted by the developer [20]. The English-to-Malay translation process was executed in four steps [23, 24]: forward-translation, expert panel consideration and back-translation, pre-testing and cognitive debriefing, and completion of the final version (see Fig. 1). First, the original instrument was forward translated from English to Malay in an independent manner by two professional bilingual native Malay speakers from the Faculty of Languages and Linguistics, Universiti Malaya. Next, two initial forward translations were discussed, with different points reconciled and harmonized to produce the pre-final MCKD-SM. Next, this pre-final MCKD-SM was assessed in terms of idiomatic, semantic, and conceptual equivalence by 10 experts (1 nephrologist, 2 nursing academicians with experience in instrument validation, 2 CKD nurse-educators, 2 family medicine specialists, and 3 patients with CKD) [25]. Both translations were reviewed by these experts prior to discussions in iteration and the reaching of a consensus on the pre-final MCKD-SM instrument.

Fig. 1

Translation and validation process

Back-translation and expert panel

Back translation from Malay to English was carried out by 2 qualified local bilingual translators (with non-medical backgrounds) who were blinded to the original English versions. The translation was re-discussed by the experts to ascertain its similarity to the original instrument, and it was agreed to move the pre-final MCKD-SM to the next stage.

Pre-testing and cognitive debriefing

When an instrument is pre-tested, cognitive debriefing is required, in which respondents are asked to verbalize what comes to mind when they hear a question [26]. For this, a sample size of 10–40 individuals is recommended [27, 28]. Therefore, the pre-final MCKD-SM was pilot tested using a purposive sample of 10 Malay-language patients with CKD recruited from the selected nephrology clinic to evaluate the instructions, response format, and the items of the instrument for clarity [25]. The participants filled in the self-administered instrument within 10–15 min. Next, they were requested to provide feedback on the clarity of the instrument’s words and sentences, as well as all aspects of its intelligibility. Subsequently, minor changes were made, such as replacing some translated terms with more commonly used terms, as suggested by the patients. For example, item 2: “Thinking over reasons about bad laboratory data” and item 13: “Don’t follow care providers’ suggestion to exercise” were translated as “Memikirkan sebab-sebab mengenai data makmal yang teruk” and “Tidak mematuhi cadangan penyedia penjagaan untuk bersenam”, respectively. In addition, the patients suggested that ‘teruk’ (bad) be replaced with ‘tidak baik’ (less good), and ‘penyedia penjagaan’ (care providers) be replaced with ‘pengamal perubatan’ (medical practitioners)”.

Instrument final version

The final MCKD-SM was then assessed for consistency, and the validation analysis was reflected in the COSMIN (COnsensus-based Standards for the selection of health Measurement INstruments) approach [29].

Phase 2: Psychometric evaluation

Psychometric measurement properties include structural validity, hypothesis testing for construct validity, internal consistency, and intra-rater test–retest reliability [22]. Exploratory factor analysis (EFA) was performed by applying principal component extraction and Promin rotation methods. In this context, the polychoric correlation method was executed, which is suitable for ordinal variables and items with the Likert-type response scale. Polychoric correlation is advised when the univariate distributions of ordinal items are asymmetric or with excess kurtosis. The Factor 10.10.02 program [30] was applied to conduct the EFA. Parallel analysis was performed to determine the number of factors using the optimal parallel analysis (random permutation) option in the software [31]. A scree plot was used to support the parallel analysis findings.

Internal consistency was examined using Cronbach's α coefficient. Cronbach’s α < 0.70 denotes inadequate consistency, while 0.70–0.90 signifies adequate internal consistency [32]. Intra-rater 2-week test–retest reliability was performed by estimating the ICC. An ICC of 0.70 is the minimum standard for reliability [33]. Similar to previous studies [15, 21], Pearson’s correlation coefficient was used to assess the correlations between kidney disease knowledge using kidney disease knowledge survey (KiKS) [34] and self-efficacy using self-efficacy managing chronic disease (SEMCD) [35] with MCKD-SM.

KiKS measures patients’ knowledge about kidney disease, especially those who do not need to undergo RRT [34]. The 28-item KiKS comprises three factors measuring general knowledge of kidney disease, kidney functions, and progression symptoms. A correct response is given a score of 1; otherwise, 0 is the score. With a total score ranging between 0 and 28, higher scores denote a higher knowledge level about kidney disease.

The 6-item SEMCD measures the self-efficacy of patients with chronic disease [35]. In this instrument, a 10-point Likert scale was employed with scores for answers ranging from 1 (not at all confident) to 10 (totally confident). With the total score ranging from 6–60, higher scores denote better self-efficacy.

It was hypothesised that MCKD-SM would correlate with KiKS and SEMCD at ~ 0.25 [22]. Correlation coefficient scores of 0.20–0.40, 0.40–0.70, 0.70–0.90, and > 0.90 indicate weak, moderate, strong, and very strong correlations, respectively [36].

Setting

This study was carried out at a nephrology clinic located in a tertiary teaching hospital situated in Kuala Lumpur, Malaysia. The patients there were referred by general practitioners from other healthcare centres. The clinic supports patients with early CKD through those who need renal replacement therapy. Patients with CKD stages 2–5 are managed by nephrologists and qualified CKD nurse-educators.

Inclusion and exclusion criteria

The following is a list of the inclusion criteria for this study:

a)

Adults with CKD stages 3–4 (defined as glomerular filtration rate of 15–59 ml/min/173 m.2, with evidence of kidney damage)

b)

Aged ≥ 18 years

c)

Able to understand, speak and read the Malay language

Additionally, the participants must not have participated in cognitive debriefing and not have been diagnosed with pre-existing cognitive/vision impairment or serious illness (cancer, stroke or dementia).

Sample size

In light of the psychometric properties analysis, the sample size was based on the 1:10 ratio for each item [25, 33], signifying that 290 participants were needed for this study because the MCKD-SM is composed of 29 items. After considering 20% incomplete responses, 363 (290/0.8) participants were invited to participate in this study. In the two-week intra-rater test–retest testing, at least 50 participants were re-invited to participate [33].

Data collection and procedure

Data collection was conducted between June 2019 and September 2020. Eligible participants were identified by researchers at the nephrology clinic and recruited using consecutive sampling. After obtaining informed consent from the participants, self-administered instruments on the MCKD-SM, KiKS and SEMCD instrument were distributed to the participants. Demographic data from the participants (gender, age, marital status, ethnicity, employment status, and academic background) were captured in a quiet room located at the clinic. Other medical information, including CKD stages, was gathered from their medical records. Retesting was performed two weeks later.

Statistical analysis

The gathered data were analysed using the Statistical Package for Social Science (SPSS) version 25.0 (SPSS, Chicago, IL) and FACTOR (10.10.02) software [30]. Descriptive statistics were generated for individual item scores and demographic data. There were no missing data since the principal investigator and research assistants were present to ensure that all participants answered all the items. Any incomplete questionnaires were asked about and clarified by the participants to obtain their responses. The EFA was deployed using principal component analysis, a crucial aspect of tool development, to ensure the content and number of factors in the initial items set. The KMO test and Bartlett’s test of sphericity were also executed.

The retained factors were determined using the following criteria: scree plot, theoretical interpretability of the resulting factor structure and eigenvalues > 1. Next, the items were chosen based on the following four criteria: conceptual coherence of items with individual factor, factor loading > 0.3 [37], no cross-factor loaded items and minimum factor membership of three items. Afterward, the internal consistency of the MCKD-SM was determined based on Cronbach’s α. Test–retest reliability was determined using the ICC with receipt of the completed retest instrument. As for hypotheses testing for construct validity, Pearson correlations among CKD self-management behaviour, kidney disease knowledge and self-efficacy were ascertained, as all scores displayed a normal distribution.