Relationship between patient practice-oriented knowledge and metabolic control in intensively treated Type 1 diabetic patients: Results of the validation of the Knowledge and Practices Diabetes Questionnaire

Aims: To validate a newly developed questionnaire for the measurement of pa tients' knowledge and practices, with particular attention to its ability i n predicting HbA(1c) levels. Research design and methods: The Knowledge and Practices Diabetes Questionnaire (KPDQ) is a questionnaire composed of two scales, investigating patient knowledge and practices. Twenty-two question s, 12 dealing with patients' knowledge and 10 relative to patients' practic es, were initially identified. Factor analysis and reliability analysis wer e used to validate the questionnaire. The ability of the two scales in pred icting metabolic control was then evaluated. The questionnaire was administ ered to a population of Type 1 diabetic subjects intensively treated and re gularly attending the diabetes outpatient clinic of Pescara General Hospita l. The mean of all HbA(1c) measurements performed after patients were taken in charge by the clinic was used as an indicator of metabolic control. Res ults: Out of 133 Type 1 patients identified, 77 (58%) filled in the questio nnaire, Respondents had a mean age (+/-SD) of 37+/-13 years and a mean diab etes duration of 13+/-9 years. The application of factor and reliability an alyses led to the definition of two final scales composed of 30 (Knowledge Score, KS) and 5 items (Practice Score, PS), respectively. Item-scale corre lation was greater than or equal to 0.40 for all the items investigated. Cr onbach's alpha coefficient exceeded the value of 0.70 for both, scales. The mean number of HbA(1c) determinations during a median period of observatio n of 4 years was of 11+/-5. The mean HbA(1c) value for the whole population was of 7.0%+/-1.4, while the proportion of patients with values less than or equal to 7.0% was of 57%. After adjusting for clinical and patient-relat ed characteristics, the KS was the only independent predictor of metabolic control. Patients in the lowest quartile of the KS showed a more than 20-fo ld increased risk of having mean HbA(1c) values greater than or equal to 7. 0% as opposed to those in the highest quartile (odds ratio, OR=23.3; p=0.00 9). No association emerged between metabolic control and PS, Conclusions: T he KPDQ presents excellent psychometric properties, The KS also shows a ver y impressive association with the mean HbA(1c) values over a period of 4 ye ars. These findings are particularly remarkable in that many studies have f ailed in documenting such a relationship. The KS can thus be considered as a quick and efficient screening tool to be used in an ambulatory setting to monitor the level of practice-oriented knowledge of patients with Type 1 d iabetes as well as to identify those subjects who need individualized educa tional interventions. Diab. Nutr. Metab. 13: 276-283, 2000. (C) 2000, Editr ice Kurtis.