High beneficial strength Clear evidence of beneficial effect. One or more Level I studies with a low risk of bias OR three or more Level II studies with a low risk of bias Moderate beneficial strength Evidence suggestive of beneficial effect. One or two Level II studies with a low risk of bias OR two or more Level III studies with a low risk of bias Low beneficial strength Insufficient evidence at present. One or more Level I through to Level IV study with a high risk of bias High non-beneficial strength No effect or a harmful effect. One or more Level I studies with a low risk of bias OR three or more Level II studies with a low risk of bias Consistency The consistency component of the ranking system of the body of the evidence assessed whether the findings were consistent across the included studies (including across a range of study populations and study designs). It was important to determine whether study results were consistent to ensure that the results were likely to be replicable or only likely to occur under certain conditions. All studies are consistent reflecting that results are highly likely to be replicable Most studies are consistent and inconsistency may be explained, reflecting that results are moderately- highly likely to be replicable Some inconsistency reflecting that results are somewhat unlikely to be replicable All studies are inconsistent reflecting that results are highly unlikely to be replicable Generalisability This component covered how well the participants and settings of the included studies could be generalised to the target population. Population issues that might influence this component included gender, age or ethnicity, or level of care (e.g. community or hospital). The generalisability continuum is presented below:
Appendix 1 Target population Worthen et al. (2012) Checklist for considering the quality of descriptive, observational prevalence studies Verey & Smith (2012) No Target population clearly defined, including: age, sex, employment, ethnicity, religion. AND No No Relevant data from gealth questionnaire of sampled persons, if appropriate No Yes Target population not clearly defined: limited data available on: age, sex, employment, ethnicity, religion. AND No No Relevant data from health questionnaire of sampled persons, if appropriate No Target population poorly defined: little or no information on age, sex, employment, ethnicity, religion. OR Yes Little or no information from relevant data from health questionnaire of sampled persons, if appropriate No Sampling method (Representativeness) Worthen et al. (2012) Checklist for considering the quality of descriptive, observational prevalence studies Verey & Smith (2012) No Sophisticated probability sampling used (e.g. stratified sampling; cluster sampling; multistage sampling; multiphase sampling) No No Simple probability sampling used (e.g., simple random sampling) No Yes No probability sampling used Yes Measurement (Reliability) Worthen et al. (2012) Checklist for considering the quality of descriptive, observational prevalence studies Verey & Smith (2012) No Standardised data-collection methods (e.g. validated clinical interview or diagnostic instrument/criteria) OR No No Reliable survey instruments (e.g. validated measure/validated screening instrument) No Yes Non-standardised data collection. OR Yes Yes Non-validated interview or non-validated measure Yes