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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

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

slide2
Development

Applications

Current Developments

development item selection
Development: Item Selection
  • Newcastle quality assessment form
  • Ottawa comprehensive list
  • Panel review
  • Critical review by experts
development grouping items
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
development identifying items
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’
newcastle ottawa quality assessment scale case control studies
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
selection
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

comparability
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.) 

exposure
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

newcastle ottawa quality assessment scale cohort studies
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
selection13
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

comparability14
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.) 

outcome
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

applications
Applications:
  • Assess quality of nonrandomized studies
  • Incorporate assessments in interpretation of meta-analytic results
  • Design, content and ease of use
steps of a cochrane systematic review
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
objective
Objective
  • Is there a relationship between hormone replacement therapy and the incidence of coronary heart disease in postmenopausal women
inclusion criteria
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
steps of a cochrane systematic review21
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
search strategy
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
steps of a cochrane systematic review23
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
data extraction
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
results
Results
  • 16 case-control or cross-sectional
  • 14 cohort
quantification of effects
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)
steps of a cochrane systematic review27
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
slide28

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

slide29

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

slide30
Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Current Use)Case-Control Studies

Selection Comparability Exposure

slide31
Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Past Use)Case-Control Studies

Selection Comparability Exposure

slide32
Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Ever Use)Case-Control Studies

Selection Comparability Exposure

slide33
Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen + Progestin Ever Use)Case-Control Studies

Selection Comparability Exposure

slide34
Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Current Use)Cohort Studies

Selection Comparability Outcome

slide35
Adjusted Effect Estimates for Coronary Heart Disease (All Events) (HRT: Estrogen Ever Use)Cohort Studies

Selection Comparability Outcome

current development validity
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’
current development reliability
Current Development: Reliability
  • Inter-rater reliability
  • Intra-rater reliability
future development scoring
Future Development: Scoring
  • Identify threshold score distinguishing between ‘good’ and ‘poor’ quality studies
the newcastle ottawa scale nos for assessing the quality of nonrandomized studies in meta analysis39

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