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Table 2 Assessment of study quality

From: Association between periodontal disease and mortality in people with CKD: a meta-analysis of cohort studies

Study year Quality indicators from the Newcastle-Ottawa scale Score
Selection Comparable Outcome assessment
1 2 3 4 5 6 7 8 9
Blach (26) 2009 * * * *     * * 6
Kshirsagar (15) 2009 * * * * * * *   * 8
Chen (16) 2011 * * * *   * * * * 8
Souza (24) 2014 * * * *   * * * * 8
Palmer (28) 2015 * * * *    *    5
Ricardo (14) 2015 * * * *    * * * 7
Chen (27) 2015   * * *   * *   * 6
Ruokonen (25) 2016 * * * *   * * * * 8
  1. Footnote: For cohort studies, 1 indicates exposed cohort truly representative; 2, non-exposed cohort drawn from the same community; 3, ascertainment of exposure; 4, outcome of interest not present at start; 5, cohorts comparable on basis of age; 6, cohorts comparable on other factor(s); 7, quality of outcome assessment; 8, follow-up long enough for outcomes to occur; and 9, complete accounting for cohorts. Each asterisk represents one star in the Newcastle-Ottawa scale system. The maximum number of stars is 2 for comparability and 1 for each of the other categories, for a total of up to 10 stars