36
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Intra-cluster correlation coefficients in adults with diabetes in primary care practices: the Vermont Diabetes Information System field survey

      , 1 , 1

      BMC Medical Research Methodology

      BioMed Central

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background

          Proper estimation of sample size requirements for cluster-based studies requires estimates of the intra-cluster correlation coefficient (ICC) for the variables of interest.

          Methods

          We calculated the ICC for 112 variables measured as part of the Vermont Diabetes Information System, a cluster-randomized study of adults with diabetes from 73 primary care practices (the clusters) in Vermont and surrounding areas.

          Results

          ICCs varied widely around a median value of 0.0185 (Inter-quartile range: 0.006, 0.037). Some characteristics (such as the proportion having a recent creatinine measurement) were highly associated with the practice (ICC = 0.288), while others (prevalence of some comorbidities and complications and certain aspects of quality of life) varied much more across patients with only small correlation within practices (ICC<0.001).

          Conclusion

          The ICC values reported here may be useful in designing future studies that use clustered sampling from primary care practices.

          Related collections

          Most cited references 20

          • Record: found
          • Abstract: found
          • Article: not found

          The Self-Administered Comorbidity Questionnaire: a new method to assess comorbidity for clinical and health services research.

          To develop the Self-Administered Comorbidity Questionnaire (SCQ) and assess its psychometric properties, including the predictive validity of the instrument, as reflected by its association with health status and health care utilization after 1 year. A cross-sectional comparison of the SCQ with a standard, chart abstraction-based measure (Charlson Index) was conducted on 170 inpatients from medical and surgical care units. The association of the SCQ with the chart-based comorbidity instrument and health status (short form 36) was evaluated cross sectionally. The association between these measures and health status and resource utilization was assessed after 1 year. The Spearman correlation coefficient for the association between the SCQ and the Charlson Index was 0.32. After restricting each measure to include only comparable items, the correlation between measures was stronger (Spearman r = 0.55). The SCQ had modest associations with measures of resource utilization during the index admission, and with health status and resource utilization after 1 year. The SCQ has modest correlations with a widely used medical record-based comorbidity instrument, and with subsequent health status and utilization. This new measure represents an efficient method to assess comorbid conditions in clinical and health services research. It will be particularly useful in settings where medical records are unavailable.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Development of a brief test to measure functional health literacy.

            We describe the development of an abbreviated version of the Test of Functional Health Literacy in Adults (TOFHLA) to measure patients' ability to read and understand health-related materials. The TOFHLA was reduced from 17 Numeracy items and 3 prose passages to 4 Numeracy items and 2 prose passages (S-TOFHLA). The maximum time for administration was reduced from 22 minutes to 12. In a group of 211 patients given the S-TOFHLA, Cronbach's alpha was 0.68 for the 4 Numeracy items and 0.97 for the 36 items in the 2 prose passages. The correlation (Spearman) between the S-TOFHLA and the Rapid Estimate of Adult Literacy in Medicine (REALM) was 0.80, although there were important disagreements between the two tests. The S-TOFHLA is a practical measure of functional health literacy with good reliability and validity that can be used by health educators to identify individuals who require special assistance to achieve learning goals.
              Bookmark
              • Record: found
              • Abstract: not found
              • Article: not found

              Statsitical Power Analysis for the Behavioral Sciences

               J Cohen,  JL Cohen,  JM Cohen (1988)
                Bookmark

                Author and article information

                Journal
                BMC Med Res Methodol
                BMC Medical Research Methodology
                BioMed Central (London )
                1471-2288
                2006
                3 May 2006
                : 6
                : 20
                Affiliations
                [1 ]General Internal Medicine, University of Vermont, 371 Pearl Street, Burlington, VT, 05401, USA
                Article
                1471-2288-6-20
                10.1186/1471-2288-6-20
                1513389
                16672056
                Copyright © 2006 Littenberg and MacLean; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Categories
                Research Article

                Medicine

                Comments

                Comment on this article