Development and validation of the renal dosing questionnaire (RDQ-13) for pharmacists

Abstract

Pharmacists, as an integral part of the healthcare team, can play a crucial role in preventing drug-related problems in patients with chronic kidney disease that arise due to inappropriate doses. This study aimed to develop and validate a new tool, the renal dosing questionnaire (RDQ-13), for pharmacists working across hospital, community, and retail pharmacy settings. A cross-sectional study was conducted from January to March 2023 among pharmacists working in different settings. The RDQ-13 scale consists of 3-sections, encompassing demographic details, a knowledge section with 6 domains, each having 4 questions with the choice of “yes/no,” an attitude section featuring a Likert scale for 4 items, and a perception section featuring a Likert scale for 3 items. The assessment of construct and discriminative validity was performed along with testing for reliability. The average variance extracted value and the composite reliability value were used for convergent validity. A total of 65 pharmacists completed the RDQ-13, but at retest n = 2 participants were dropped (response rate at retest was 96.9%). Exploratory factor analysis revealed 3-factor loadings with 59.1% of the variance, whereas the Kaiser–Mayer–Olkin value was 0.60. The Cronbach alpha value of 0.700 indicates good internal consistency, whereas the intraclass correlation coefficient (ICC) for the test and retest showed that most domains/scores were statistically significant (P < .001), showing an excellent agreement between the test and retest. The RDQ-13 underwent extensive validation through a cross-sectional survey, demonstrating high content and face validity. The scale showed consistent responses over time (test–retest stability) and good internal consistency.

1. Introduction

Chronic kidney disease (CKD) is a major public health concern, affecting more than 10% of the population worldwide,^[1,2] with a higher prevalence reported in Asian countries (up to 18%).^[3] Despite best efforts to provide timely referrals and comprehensive care, the incidence and mortality rates associated with CKD are increasing at an alarming rate.^[4] There has been a substantial (29.3%) increase in the prevalence of CKD since 1990 and a 41.5% increase in global mortality from the disease as of 2017.^[5] According to current statistics, approximately 700 million people are estimated to have CKD worldwide.^[6] The literature suggests that low- and middle-income countries are more significantly impacted by CKD,^[2] with the incidence rate being 4 times higher than that in developed countries.^[1]

CKD exhibits a heightened prevalence among the elderly, women, and individuals concurrently experiencing co-morbidities, notably hypertension and diabetes, making polypharmacy inevitable in these patients, thereby increasing the potential of drug-related complications.^[7] Among patients with CKD, the pharmacokinetic and pharmacodynamic parameters of renally excreted drugs are altered, leading to higher plasma drug concentrations and increased chances of drug toxicity. Additionally, patients with CKD are more vulnerable to adverse drug reactions (ADRs) and potential harm if a drug requiring dose adjustment is left unadjusted or a contraindicated drug is prescribed.^[8] Despite existing dosing adjustment guidelines, inappropriate dose adjustment is still a frequent drug-related problem (DRPs), a systematic review based on 20 studies showed that the prevalence of DRPs in cases of CKD ranged from 12% to 87%.^[9]

Since the DRPs among CKD patients are most common, the valuable contribution of pharmacists toward drug therapy has been established for improvement in clinical outcome.^[10,11] Pharmacists, as members of the healthcare team, are the most suitable healthcare professionals to deal with drug-related problems among patients with CKD because of their clinical training and knowledge regarding the pharmacokinetic and pharmacodynamic parameters of drugs. They can play a vital role in ensuring the safety of patients by offering various services such as medication screening for drug–drug interactions, dose adjustment of nephrotoxic drugs, therapeutic drug monitoring, and patient counseling. Due to the complex medication regimen In CKD patients resulting from multiple co-morbidities the effective management requires a multidisciplinary healthcare team including a pharmacist.^[12] Literature supports the role of the pharmacist in improving the healthcare team’s ability to promote safe, effective drugs.^[11]

As pharmacists are important players in ensuring safety and rational therapy for patients with CKD, it is crucial to assess pharmacists’ knowledge, perception, and attitude toward renal dose adjustments. After a comprehensive literature search, no suitable, in-depth tool was found to implement this assessment, creating the urge to develop and validate a new scale to assess these aspects of pharmacists. This study aimed to develop and evaluate the reliability and validity of the RDQ-13 scale among pharmacists working in hospital, community, and retail pharmacy settings.

2. Methods

A cross-sectional survey was conducted from January to March 2023 among pharmacists working in different settings, including hospitals, retail, and community pharmacies.

2.1. Development of the RDQ-13 scale

2.1.1. Item generation

To create the items, a comprehensive literature review was conducted. A new scale to evaluate pharmacists’ knowledge, attitude, and perception regarding renal dosage adjustment needs to be developed and validated because the research showed that there was no adequate and comprehensive tool available for this purpose.

2.1.2. Item selection

We conducted a content validity analysis to determine if the original pool of items accurately reflected the RDQ-13 construct. For this purpose, 8 specialists were selected on the basis of their subject matter competence. The experts included consultant nephrologists, clinical pharmacy specialists, psychologists, and university lecturers with expertise in psychometrics. Specifically, each item was rated by the experts using a “4-response” scale: absolutely necessary = 3, necessary = 2 useful, but not required = 1, Not useful, must be deleted = 0). To assess content validity, the scale-level content validity index (S-CVI) and the item-level content validity index (I-CVI) were generated.^[13] Values of the I-CVI that are <0.7 require removal; those that are between 0.7 and 0.79 indicate that adjustment is required; and values that are more than 0.79 are considered appropriate. Values of the S-CVI that are more than 0.8 are demonstrative of the tool’s acceptable content validity.^[13] After the assessment of content validity, face validity was evaluated through the administration of the preliminary questionnaire to a cohort of 10 pharmacists. Participants were tasked with rating the face validity of each item on a 10-point scale, considering attributes such as comprehension, unambiguity, clarity, and susceptibility to misinterpretation. The mean scores were computed for each criterion, which encompassed understanding ability, unambiguity, clarity, chance of misinterpretation, and the overarching measure of overall face validity. The questionnaire’s timing, comprehension, phrasing clarity, arrangement, style, and completeness were all evaluated. Feedback on the questionnaire’s layout, substance, and organization was also welcomed from participants. The clarification and readability of the questionnaire were improved by taking into consideration the small recommendations made by the respondents.

2.2. Instrument (RDQ-13 scale)

The RDQ-13 is the first scale of its kind to assess the knowledge, attitude, and perception of pharmacists toward renal dose adjustment in depth. This 13-item scale took only 5 to 7 minutes to answer and measured pharmacists’ knowledge, attitude, and perception regarding renal dosing in patients with CKD. The RDQ-13 was created in English because the respondents graduated from institutions where the language of teaching and instruction was English. The questionnaire was self-administered to avoid interviewer bias. The RDQ-13 comprised demographic questions (gender, age, working experience in years, educational qualification, work setting, designation of the pharmacist, and available drug reference[s]), while the knowledge section comprised 6 domains with 4 questions in each domain with options of “yes” and “no.” A score of 1 was assigned to” yes” while a zero score was assigned to “no,” and the maximum score for all 6 domains was set as 24. The attitude of the pharmacist was assessed on a Likert scale with 4 questions with a score of 0 to 3, and the maximum score set for this section was 12. The assessment of pharmacist perception was performed using a Likert scale with 3 questions, with a score of 1 to 4 for 2 questions and 0 to 3 for the last question. The maximum score assigned to this section was 11. Two additional questions regarding the significant barriers to renal dose adjustment and interest in attending courses and/or continuing medical education related to renal dose adjustments were incorporated (attached as Appendix 1, Supplemental Digital Content http://links.lww.com/MD/O222).

2.3. Participants

To assess the validity and reliability of the RDQ-13 scale, the inclusion criteria set for this study comprised of pharmacists of both genders and of any age working as hospital pharmacists, clinical pharmacists, community or retail pharmacists in the major cities of Khyber Pakhtunkhwa province, Pakistan.

2.4. Sample size and ethical approval

To evaluate the validity and reliability of the newly developed RDQ-13 scale, the sample size was calculated on the basis of the number of items to participant ratio, i.e., 1:5.^[14] Because the RDQ-13 comprised 13 items, the minimum sample size required for validation and reliability was 65 participants. The study was approved by the ethical committee of relevant institution (attached as Appendix 2, Supplemental Digital Content, http://links.lww.com/MD/O222).

2.5. Procedure

Informed written consent was obtained from each pharmacist for participation in this study by explaining the purpose of the study and the newly developed RDQ-13 scale. As per the sample size specified, a total of n = 65 pharmacists were approached in person to complete RDQ-13. At baseline (test), the RDQ-13 was filled in by pharmacists who met the inclusion criteria, and after 2 weeks (retest), the RDQ-13 was filled in again by the same pharmacists via the same mode to examine the agreement between the repetitive measures for intraclass correlation coefficient (ICC).

2.6. Statistical analysis

The Statistical Package for Social Sciences version 22.0^® (SPSS Inc., Chicago, IL, USA) was used for data analysis. To determine the normality of the data, the Shapiro–Wilks test was used.^[15] Our data were not normally distributed; therefore, median and interquartile range (IQR) were reported for continuous variables, whereas frequency and percentage were used for categorical variables.

2.6.1. Validity

To determine the construct validity of the RDQ-13, exploratory factor analysis employing principal component analysis and varimax rotation was used to identify items with a factor loading of 0.4.^[16] Questions related to knowledge (domains 1–6), attitude, and perception were used to perform the validity rating. Factors exhibiting an eigenvalue surpassing 1 were deemed substantial contributors in elucidating the overall model variation and were consequently retained. Sampling adequacy was evaluated through multiple metrics, including Bartlett test of sphericity, the Kaiser–Mayer–Olkin (KMO) measure, factor loadings, average variance extracted (AVE), and composite reliability (CR). A good model of fit had values >0.7, 0.5, 0.5, and 0.6.^[16] To evaluate the discriminative validity of RDQ-13, the Mann–Whitney U test was employed to determine whether a significant difference existed in the test–retest responses among participants. A P-value of < .05 was considered statistically significant.

2.6.2. Reliability

To assess the internal consistency of RDQ-13, Cronbach alpha was used. Questions related to knowledge (domains 1–6), attitude, and perception were used to perform the reliability rating. A value >0.70 indicated good internal consistency.^[17] The agreement between the repetitive measures, i.e., test–retest, was assessed using the ICC. The ICC values of >0.75 indicate excellent agreement, 0.60 to 0.74 indicate good agreement, values ranging from 0.40 to 0.59 show fair to moderate agreement, and values < 0.40 indicate poor agreement.^[18]

3. Results

A total of n = 65 participants were approached, and all agreed to participate in the validation of the RDQ-13 scale. However, at the retest, n = 2 participants were dropped for not filling in the RDQ-13. Response rate at retest was 96.9%. The majority of participants were male (66.2%) and in the 20-to 30-year-old age bracket (55.4%). Regarding professional experience, most participants (61.5%) had <5 years of professional experience and (69.2%) were working in a hospital setting as hospital pharmacists, with 63.1% having Pharm. D. The majority (56.9%) were working as designated staff pharmacists, while 46.2% were using medscape/renal dosing handbook/mobile applications, etc as drug references for their clinical practice/dose adjustment of CKD patients (details are shown in Table 1).

Table 1.

Demographic characteristics of participants (n = 65).

	N	%
Gender
Male	43	66.2
Female	22	33.8
Age in years
20 to 30 yr	36	55.4
31 to 40 yr	25	38.5
41 to 50 yr	4	6.2
Professional experience
<5 yr	40	61.5
5 to 10 yr	18	27.7
11 to 15 yr	3	4.6
˃16 yr	4	6.2
Education
Bachelor of Pharmacy	2	3.1
Doctor of Pharmacy (Pharm D)	41	63.1
Higher degree	20	30.8
Other professional certificate/board certified pharmacotherapy specialist	2	3.1
Working setting
Hospital Pharmacy	45	69.2
Clinical Pharmacy	11	16.9
Community Pharmacy	5	7.7
Retail Pharmacy	4	6.2
Designation
Trainee Pharmacist	6	9.2
Resident Pharmacist	7	10.8
Staff Pharmacist	37	56.9
Assistant Manager Pharmacy	5	7.7
Manager Pharmacy	6	9.2
Chief Pharmacist	4	6.2
Drug reference available
British National Formulary	10	15.4
British/US pharmacopeia	7	10.8
Lexicomp	9	13.8
Micromedex	9	13.8
Others (medscape, renal dosing handbook, mobile applications, etc)	30	46.2

3.1. Item purification and validation

The findings of content validity revealed that the I-CVI ranged from 0.5 to 1. However, the S-CVI/Average obtained was 0.838, indicating an overall acceptable level of content validity. For face validity, the average score (out of 10) was 8.71 ± 0.3, whereas specific scores were obtained for other aspects such as level of understanding (8.52 ± 0.39), unambiguity (8.41 ± 0.42), clarity (8.84 ± 0.34), and the likelihood of misinterpretation (7.98 ± 0.65).

Exploratory factor analysis with varimax rotation of the RDQ-13 revealed 3-factor loadings (shown in Table 2) and accounted for 59.1% of the variance (KMO = 0.60, chi-square = 63.430, Bartlett test of sphericity was significant [df = 28, P < .001] for knowledge [domain 1–6], attitude, and perception questions). The discriminative validity evaluated via the Mann–Whitney U test revealed no significant difference between the test and retest (shown in Table 3). The findings indicate that the participants interpreted most of the items similarly at the test and retest, indicating that the scale was stable. Moreover, to assess the convergent validity, the AVE value and CR values were employed. In our investigation, the AVE values were 0.520, 0.762, and 0.479, respectively, and the corresponding CR values were 0.764, 0.517, and 0.641, respectively (Table 2). The RDQ-13 showed good internal consistency with a Cronbach alpha of 0.700 for knowledge (domains 1–6), attitude, and perception-related questions. During the retest phase, 2 participants were no longer available. The ICC analysis conducted at both the initial test and retest stages indicated statistically significant findings (P < .001) for most items/domains of scale (shown in Table 4) and demonstrated excellent agreement between the test and retest.

Table 2.

Item factor loading based on principal component analysis with varimax rotation of RDQ-13 scale.

	Factors			CR	AVE
	1	2	3
Attitude score	0.666			0.764	0.520
Perception score	0.732
Domain1: Related to renal dose adjustment	0.763
Domain 2: Factors to be considered when determining the appropriate dose for a patient with renal impairment		0.751		0.517	0.762
Domain 3: Medications commonly require renal dose adjustment		0.708
Domain 6: Resources to determine the appropriate dose for a patient with renal impairment		0.697
Domain 4: Calculating the appropriate dose for a patient with renal impairment			0.796	0.641	0.479
Domain 5: Consequences of not adjusting the dose of medications for patients with renal impairment			0.569

Extraction method: principal component analysis. Rotated method: varimax. Domain 1 to 6 are related to knowledge score. The sequence of domains is not in flow because it is based on the loading factors, its CR and AVE.

Abbreviations: AVE = average variance extracted, CR = composite reliability.

Table 3.

Participants score at test (baseline) and retest for RDQ-13 scale.

Domains	Test (n = 65)		Retest (n = 63)		Mann–Whitney U test
	Median	IQR	Median	IQR	P-value
Domain 1	3.00	3.00 to 4.00	4.00	3.00 to 4.00	0.024*
Domain 2	4.00	4.00 to 4.00	4.00	4.00 to 4.00	0.009*
Domain 3	4.00	3.00 to 4.00	4.00	3.00 to 4.00	0.024*
Domain 4	4.00	4.00 to 4.00	4.00	4.00 to 4.00	0.028*
Domain 5	4.00	4.00 to 4.00	4.00	4.00 to 4.00	0.756
Domain 6	4.00	4.00 to 4.00	4.00	4.00 to 4.00	0.346
Overall knowledge score	22.00	20.00 to 23.00	23.00	22.00 to 23.00	0.003*
Attitude score	11.00	10.00 to 12.00	11.00	10.00 to 12.00	0.849
perception score	9.00	8.00 to 10.00	10.00	9.00 to 10.00	0.029*

Abbreviation: IQR = interquartile range.

^*Statistically significant at P < .05; Domains 1 to 6 are related to knowledge score. Domain 1: Related to renal dose adjustment; Domain 2: Factors to be considered when determining the appropriate dose for a patient with renal impairment; Domain 3: Medications commonly require renal dose adjustment; Domain 4: Calculating the appropriate dose for a patient with renal impairment; Domain 5: Consequences of not adjusting the dose of medications for patients with renal impairment; Domain 6: Resources to determine the appropriate dose for a patient with renal impairment.

Table 4.

The psychometric properties of the RDQ-13 scale.

Domain	Cronbach alpha for overall instrument	Corrected item-total correlation	Cronbach alpha if the item deleted	Test (n = 65)	Retest (n = 63)	Intraclass correlation coefficient*
				Median	Median
Domain 1	0.700	0.513	0.654	3.00	4.00	0.791*
Domain 2		0.411	0.689	4.00	4.00	0.847*
Domain 3		0.351	0.680	4.00	4.00	0.896*
Domain 4		0.305	0.690	4.00	4.00	0.821*
Domain 5		0.373	0.677	4.00	4.00	0.933*
Domain 6		0.342	0.692	4.00	4.00	0.893*
Attitude score		0.334	0.692	11.00	11.00	0.985*
Perception score		0.297	0.694	9.00	9.00	0.802*

Cronbach alpha was calculated for overall scale including knowledge (domains 1–6), attitude and perception questions.

^*Statistically significant at P < .05; Domain 1 to 6 are related to knowledge score. Domain 1: Related to renal dose adjustment; Domain 2: Factors to be considered when determining the appropriate dose for a patient with renal impairment; Domain 3: Medications commonly require renal dose adjustment; Domain 4: Calculating the appropriate dose for a patient with renal impairment; Domain 5: Consequences of not adjusting the dose of medications for patients with renal impairment; Domain 6: Resources to determine the appropriate dose for a patient with renal impairment.

4. Discussion

This study validated a new scale for pharmacists’ knowledge, attitudes, and perceptions regarding renal dose adjustments. Because this study was the first of its kind among pharmacists in Pakistan, most participants showed interest in completing the questionnaire, which is evident from their response rate (96.9%). Renal dose adjustment is an important parameter for improving the quality of life of patients with CKD by promoting the right dose of the drug requiring dose adjustment to prevent subsequent drug toxicities. In developing countries, including Pakistan, the incidence of CKD is increasing at an alarming rate. Pharmacists are an integral part of the healthcare team and are in the right position to prevent drug-related problems, as evident from the current literature.^[19–22] Given that, to date, no validated scale exists to determine the knowledge, attitude, and perceptions of pharmacists regarding renal dose adjustment, a new scale (RDQ-13) was developed and validated for this purpose.

Exploratory factor analysis was performed in this study, which is considered to be a powerful multivariate analysis for investigating the relationship between variables and examining the construct validity of the scale.^[23,24] In our study, construct validity was measured using varimax rotation and the principal component method. The KMO of the RDQ-13 was 0.60, which falls under the category of acceptable range,^[25] and the variance explained in our study was 59.07%. These were above the recommended level of at least 30%. The RDQ-13 scale consisted of 3-factor loadings, and naming these factors was a challenge because some items did not fit into a single group. The naming of the factors is subjective and reflects conceptual intention.^[26] The criterion for the exploratory factor analysis was a factor loading of at ≥0.4 for each item. Furthermore, for convergent validity, the AVE values in our study were 0.520, 0.762, and 0.479, respectively, while the CR values were 0.764, 0.517, and 0.641, respectively, which are aligned with the standard values.^[16]

To assess the reliability and agreement of the repetitive measures of RDQ-13, ICC was performed. Our study findings revealed an RDQ-13 scale with a reliability of 0.700, and most domains/scores showed statistically significant agreement (P < .001) at repeated measurement for ICC, which is consistent with the standard reference values.^[27,28] Hence, based on these results, the RDQ-13 scale was a reliable and validated scale for assessing pharmacists’ knowledge, attitude, and perception of renal dose adjustments.

5. Strengths and limitations of this study

The RDQ-13 scale was introduced as the first in-depth tool to assess pharmacists’ knowledge, attitude, and perception of renal dose adjustment, filling a significant gap in the existing literature. This aspect can be further emphasized because it provides a significant contribution to the field. A possible limitation of this study was that it was performed among pharmacists working in 1 province, namely Khyber Pakhtunkhwa; hence, the addition of pharmacists working in other provinces might improve the sample representativeness and explore the cultural differences represented by different regions of Pakistan. Another limitation of our study was the risk of social desirability bias, as the pharmacists may have provided socially desirable responses rather than truthful responses to avoid being seen in a negative light, which can limit the accuracy and usefulness of the data collected.

6. Conclusion

The RDQ-13 scale is a pioneering tool designed to provide an in-depth evaluation of the knowledge, attitudes, and perceptions of pharmacists working in various settings regarding renal dosage adjustment. Through a cross-sectional survey conducted among pharmacists in hospital, community, and retail settings, the RDQ-13 scale underwent rigorous content and face validity assessments. The content validity indices (I-CVI and S-CVI) demonstrated acceptable levels of content validity. Face validity was also established with high average scores, reflecting the questionnaire’s comprehension, unambiguity, clarity, and minimal susceptibility to misinterpretation. Exploratory factor analysis revealed 3-factor loadings, accounting for 59.1% of the variance, suggesting a solid construct validity. These factors were related to the knowledge, attitude, and perception domains of RDQ-13. Discriminative validity showed no significant difference in responses between the test and retest phases. In terms of reliability, the RDQ-13 demonstrated good internal consistency with a Cronbach alpha of 0.700 for the knowledge, attitude, and perception sections. The ICC values indicated excellent agreement between the initial test and retest phases for most items/domains. The effectiveness of the RDQ-13 scale in reliably and validly assessing pharmacists’ knowledge, attitudes, and perceptions regarding renal dose adjustment for patients with CKD was confirmed.

Author contributions

Conceptualization: Roheena Zafar, Inayat ur Rehman, Yasar Shah, Long Chiau Ming.

Data curation: Roheena Zafar.

Formal analysis: Roheena Zafar, Inayat ur Rehman, Yasar Shah, Muhammad Abdul Hadi, Amal K Suleiman.

Investigation: Roheena Zafar, Inayat ur Rehman, Long Chiau Ming, Muhammad Abdul Hadi, Amal K Suleiman, Khang Wen Goh.

Methodology: Roheena Zafar, Inayat ur Rehman, Yasar Shah, Long Chiau Ming, Muhammad Abdul Hadi, Amal K Suleiman, Khang Wen Goh.

Project administration: Khang Wen Goh.

Resources: Roheena Zafar.

Supervision: Inayat ur Rehman, Yasar Shah.

Validation: Roheena Zafar, Inayat ur Rehman, Long Chiau Ming.

Visualization: Khang Wen Goh.

Writing – review & editing: Inayat ur Rehman, Long Chiau Ming, Muhammad Abdul Hadi, Amal K Suleiman, Khang Wen Goh.

Writing – original draft: Roheena Zafar, Yasar Shah.