At baseline, a sociodemographic questionnaire was used to
obtain demographic information, cause of kidney failure, dry
weight, duration of dialysis, phosphate binders and urine.
The knowledge questionnaire was developed by researchers.
This is a Chinese-language questionnaire containing
17 items that cover four domains: harmfulness ofhyperphosphataemia, knowledge related to phosphorus
food restriction, knowledge of phosphate binders and subjects’
compliance with diet and medication. The first 12
items are of multiple-choice format, two marks for a correct
answer and 0 if incorrect. We adopted a four-level
scoring method to assess patients’ compliance (items
13–16), a score of 3 represents never and 0 represents
always. The last item is an open-ended question to evaluate
the reason of poor medication compliance (not graded).
The total score is 36 points. Thirty participants were
included to complete the knowledge questionnaire to test
its validity and reliability in our pilot study. Principle component
analysis was used to evaluate its validity. At first,
results of the exploratory factor analysis showed that the
questionnaire was appropriate for factor analysis (KMO
was 071, the chi-square value of Bartlett’s test was 38011,
and the significance was