Development and Validation of the Rating of CKD Knowledge Among Older Adults (Know-CKD) with Kidney Failure.

RATIONALE & OBJECTIVE: Few older adults with kidney failure engage in shared decision-making (SDM) for kidney replacement therapy. Absence of instruments assessing SDM-relevant knowledge domains may contribute to this. We assessed the reliability and validity of a new instrument, the Rating of CKD Knowledge Older Adults (Know-CKD).

STUDY DESIGN: Multi-stage process, including a stakeholder-engaged development phase, pilot testing, and validation of a knowledge instrument using a cross-sectional survey of older adults with CKD.

SETTING & PARTICIPANTS: The study population consisted of 363 patients 70+ years with non-dialysis advanced CKD (eGFR less than 30 mL/min/1.73 m2 ) in Boston, Chicago, Portland, ME, and San Diego from June 2018 and January 2020.

ANALYTICAL APPROACH: Reliability was assessed with the Kuder-Richardson-20 coefficient. Construct validity was demonstrated by testing a priori hypotheses using t-test, analysis of variance (ANOVA) tests, and linear regression analyses.

EXPOSURES: Educational level, higher literacy (Single Item Literacy Screener (SILS)) and numeracy (Subjective Numeracy Scale (SNS)), having participated in clinic-sponsored dialysis education, and self-reported "feeling informed" about options for treatment.

OUTCOME: Validity and reliability of the Know-CKD instrument.

RESULTS: Mean participant age was 77.6 ± 5.9 years, mean eGFR was 22.7 ± 7.2 mL/min/1.73 m2 , 281 (78%) self-reported as White. The 12-item Know-CKD assessment had good reliability (Kuder-Richardson-20 reliability coefficient = 0.75), and a mean score of 58.2% (SD ±22.3). The subscales did not attain acceptable reliability. The proportion answering correctly on each item ranged from 20.1% to 91.7%. In examining construct validity, hypothesized associations held, with Know-CKD significantly associated with higher education (β = 6.98; 95% CI, 1.34-12.61; p = 0.02), health literacy (β = -12.67; 95% CI, -19.49 to -5.86; p ≤0.001), numeracy per 10% higher (β = 1.85; 95% CI, 1.02-2.69; p≤0.001), and attendance at dialysis class (β = 18.28; 95% CI, 13.30-23.27; p≤0.001). These associations were also observed for the subscales, save prognosis (not associated with literacy or numeracy).

LIMITATIONS: Know-CKD is only available in English and has been used only in research settings.

CONCLUSIONS: For older adults facing dialysis initiation decisions, Know-CKD is a valid, reliable, and easy to administer measure of knowledge. Further research should examine the relationship of kidney disease knowledge and SDM, patient satisfaction, and clinical outcomes.