Developing a self-administered CKD symptom assessment instrument.

BACKGROUND: Current disease-centred therapies for CKD focus on preserving the GFR but often ignore patient-reported symptoms. This purpose of this report is to describe the development of an instrument to measure the presence and severity of a wide range of symptoms commonly attributable to CKD.
METHODS: A 37-item questionnaire was administered along with the Kidney Disease Quality of Life instrument to 92 patients with CKD not on dialysis (24% black, 5% women, mean age 68 years, 68% with diabetes mellitus). To discover groups of symptoms, agglomerative cluster analysis followed by exploratory common factor analysis was performed. Construct validity, internal reliability, convergent and discriminant validity, test-retest reliability and finally the association of various symptom domains with objective measurements such as estimated GFR and haemoglobin were tested.
RESULTS: The top five symptoms of at least moderate severity in decreasing order of prevalence were 'tire easily', limited physical activity, nocturia, joint pain and 'stop and rest often'. Four common factors emerged that could be broadly classified into neuropsychiatric, cardiovascular, uraemia and anaemia symptoms accounting for 73% of the total variance in the sample. The coefficient alpha for each of these factors approached 0.9. The test-retest reliability in 41 patients over 8 weeks was likewise high. There was good convergent and divergent validity. However, there was little relationship between estimated GFR and symptom scores.
CONCLUSIONS: The assessment of symptom burden among patients with CKD may be facilitated by incorporating this instrument in routine practice and clinical trials.