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The Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Nonrandomized Studies in Meta-Analysis

The Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Nonrandomized Studies in Meta-Analysis . G. Wells, B. Shea, D. O’Connell, J. Robertson, J. Peterson, V. Welch, M. Losos, P. Tugwell. Development Applications Current Developments. Development: Item Selection.

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The Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Nonrandomized Studies in Meta-Analysis

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  1. The Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Nonrandomized Studies in Meta-Analysis G. Wells, B. Shea, D. O’Connell, J. Robertson, J. Peterson, V. Welch, M. Losos, P. Tugwell

  2. Development Applications Current Developments

  3. Development: Item Selection • Newcastle quality assessment form • Ottawa comprehensive list • Panel review • Critical review by experts

  4. Development: Grouping Items • Cohort studies • Selection of cohorts • Comparability of cohorts • Assessment of outcome • Case-Control studies • Selection of case and controls • Comparability of cases and controls • Ascertainment of exposure

  5. Development: Identifying Items • Identify ‘high’ quality choices with a ‘star’ • A maximum of one ‘star’ for each h item within the ‘Selection’ and ‘Exposure/Outcome’ categories; maximum of two ‘stars’ for ‘Comparability’

  6. Newcastle-Ottawa Quality Assessment Scale: Case-Control Studies • Selection (4) • Comparability (1) • Exposure (3) • A study can be awarded a maximum of one star for each numbered item within the Selection and Exposure categories. A maximum of two stars can be given for Comparability

  7. Selection 1. Is the case definition adequate? a) yes, with independent validation  b) yes, eg record linkage or based on self reports c) no description 2. Representativeness of the cases a) consecutive or obviously representative series of cases  b) potential for selection biases or not stated 3. Selection of Controls a) community controls  b) hospital controls c) no description 4. Definition of Controls a) no history of disease (endpoint)  b) no description of source e.g. ICD codes in database or self-report with no reference to primary record or no description >1 person/record/time/process to extract information, or reference to primary record source such as x-rays or medical/hospital records

  8. Comparability 1. Comparability of cases and controls on the basis of the design or analysis a) study controls for ___________ (select the most important factor)  b) study controls for any additional factor (This criteria could be modified to indicate specific control for a second important factor.) 

  9. Exposure 1. Ascertainment of exposure a) secure record (eg surgical records)  b) structured interview where blind to case/control status  c) interview not blinded to case/control status d) written self report or medical record only e) no description 2. Same method of ascertainment for cases and controls a) yes  b) no 3. Non-Response Rate a) same rate for both groups  b) non respondents described c) rate different and no designation

  10. Newcastle-Ottawa Quality Assessment Scale: Cohort Studies • Selection (4) • Comparability (1) • Outcome (3) • A study can be awarded a maximum of one star for each numbered item within the Selection and outcome categories. A maximum of two stars can be given for Comparability

  11. Selection 1. Representativeness of the exposed cohort a) truly representative of the average ___________ (describe) in the community  b) somewhat representative of the average ___________ in the community  c) selected group of users eg nurses, volunteers d) no description of the derivation of the cohort 2. Selection of the non exposed cohort a) drawn from the same community as the exposed cohort  b) drawn from a different source c) no description of the derivation of the non exposed cohort 3. Ascertainment of exposure to implants a) secure record (eg surgical records)  b) structured interview  c) written self report d) no description 4. Demonstration that outcome of interest was not present at start of study a) yes  b) no In the case of mortality studies, outcome of interest is still the presence of a disease/ incident, rather than death; that is a statement of no history of disease or incident earns a star

  12. Comparability 1. Comparability of cohorts on the basis of the design or analysis a) study controls for ___________ (select the most important factor)  b) study controls for any additional factor (This criteria could be modified to indicate specific control for a second important factor.) 

  13. Outcome 1. Assessment of outcome a) independent blind assessment  b) record linkage  c) self report d) no description 2. Was follow up long enough for outcomes to occur a) yes (select an adequate follow up period for outcome of interest)  b) no 3. Adequacy of follow up of cohorts a) complete follow up - all subjects accounted for  b) subjects lost to follow up unlikely to introduce bias - small number lost - > ___ % (select an adequate %) follow up, or description of those lost)  c) follow up rate < ___% (select an adequate %) and no description of those lost d) no statement

  14. Applications: • Assess quality of nonrandomized studies • Incorporate assessments in interpretation of meta-analytic results • Design, content and ease of use

  15. Long Term Hormone Replacement Therapy and Coronary Heart Disease Events

  16. Steps of a Cochrane Systematic Review • Clearly formulated question • Comprehensive data search • Unbiased selection and abstraction process • Critical appraisal of data • Synthesis of data • Perform sensitivity and subgroup analyses if appropriate and possible • Prepare a structured report

  17. Objective • Is there a relationship between hormone replacement therapy and the incidence of coronary heart disease in postmenopausal women

  18. Inclusion Criteria • Types of studies • case-control, cohort or cross-sectional studies • Population • postmenopausal women • Intervention • women exposed to hormone replacement therapy (estrogen or estrogen + progesterone) • ever, current, past • Outcomes • coronary heart disease (events) • fatal, non-fatal, both

  19. Steps of a Cochrane Systematic Review • Clearly formulated question • Comprehensive data search • Unbiased selection and abstraction process • Critical appraisal of data • Synthesis of data • Perform sensitivity and subgroup analyses if appropriate and possible • Prepare a structured report

  20. Search Strategy • Electronic Search of: • MEDLINE (1966 to May 2000) • Current Contents (to May 2000) • Other Data Sources: • review of references cited in retrieved articles

  21. Steps of a Cochrane Systematic Review • Clearly formulated question • Comprehensive data search • Unbiased selection and abstraction process • Critical appraisal of data • Synthesis of data • Perform sensitivity and subgroup analyses if appropriate and possible • Prepare a structured report

  22. Data Extraction • 2 independent reviewers selected trials • 2 independent reviewers extracted data using pre-determined forms • study design • population characteristics • exposure to implants • outcomes measures • results • differences resolved by consensus

  23. Results • 16 case-control or cross-sectional • 14 cohort

  24. Quantification of Effects • Exposure (ever, current, past) • Outcome (fatal, non-fatal, both) • Effect estimates (EE) • Relative Risk (RR) • Odds Ratio (OR) • Adjusted effect estimates • Effects vs population, follow-up periods, etc. (homogeneity)

  25. Steps of a Cochrane Systematic Review • Clearly formulated question • Comprehensive data search • Unbiased selection and abstraction process • Critical appraisal of data • Synthesis of data • Perform sensitivity and subgroup analyses if appropriate and possible • Prepare a structured report

  26. Cohort Star Template Selection Comparability Outcome Avila / 90 Bush / 87 Cauley / 97 Criqui / 98 Ettinger / 96 Folsom / 95 Grodstein / 96 Henderson / 91 Lafferty / 94 Lauritzen / 83 Petitti / 87 Sourander / 98 Wilson / 85 Wolf / 96

  27. Case-Control Star Template Selection Comparability Exposure Adam / 81 Beard / 89 Croft / 89 Grodstein / 97 Heckbert / 97 LaVecchia / 87 Mann / 94 Pfeffer / 78 Rosenberg / 76 Rosenberg / 80 Rosenberg / 93 Ross / 81 Sidney / 97 Szklo / 84 Talbott / 77 Thompson / 89

  28. Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Current Use)Case-Control Studies Selection Comparability Exposure

  29. Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Past Use)Case-Control Studies Selection Comparability Exposure

  30. Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Ever Use)Case-Control Studies Selection Comparability Exposure

  31. Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen + Progestin Ever Use)Case-Control Studies Selection Comparability Exposure

  32. Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Current Use)Cohort Studies Selection Comparability Outcome

  33. Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Ever Use)Cohort Studies Selection Comparability Outcome

  34. Current Development: Validity • Face/content validity • Criterion validity • compare to more comprehensive scales • compare to expert judgement • Construct validity • external criteria • ‘convergent validity’ • ‘divergent validity’ • internal structure • ‘factorial validity’

  35. Current Development: Reliability • Inter-rater reliability • Intra-rater reliability

  36. Future Development: Scoring • Identify threshold score distinguishing between ‘good’ and ‘poor’ quality studies

  37. The Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Nonrandomized Studies in Meta-Analysis www.lri.ca NOS Quality Assessment Scales: Case-control studies Cohort studies Manual for NOS Scales

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