Table 2

Case-controlled studies: Newcastle-Ottawa Scale for the assessment of quality of included case-controlled studies

Acceptable criteriaZilkens et al  18 Boot et al 19
 Case definitionWith independent validationRecord linkage from Western Australian Data Linkage System and Death Registry, no independent validationAssessment for DLB using behavioural neurologist+
 Representativeness of casesConsecutive or representative series of casesAll dementia cases in period 2000–2009 identified via read code; lower limit index dementia age 65 years, upper limit 84 years; dementia in other diseases excluded+Recruited from longitudinal studies in period 1984–2013 (Alzheimer Disease Patient Registry, Alzheimer Disease Research Center Study and Mayo Clinic Study of Aging); community-dwelling persons aged 70–89 years; excluded structural brain lesions+
 Selection of controlsCommunity controlsPopulation controls; randomly selected from electoral role aged ≥65 years prior to extraction of health data for controls+Community controls from longitudinal study of ageing; individuals aged ≥65 years; selected if seen by physician in same month as clinical subject diagnosed; matched by age and sex+
 Definition of controlsNo history of diseaseExcluded if dementia read code in records; no independent screening+Excluded if diagnosed with DLB/AD during the study, previous stroke, head injury, neurological disease or movement disorder; extensive cognitive and medical examination+
 Comparability of cases and controls on basis of design and analysisStudy controls for the most important factor (+/−) and any additional factor (+/−)Controls for age, sex, vascular risk factors (diabetes, IHD, AF, CVD, hypertension, hyperlipidaemia, heart failure and past or current smoking), head injury, alcohol dependence syndrome and depression++Controls for age, sex; multivariate analyses control for family history, depression, APOE ε4 alleles, education level, head injury, cancer and vascular risk factors (stroke, diabetes, alcohol, smoking)++
 Ascertainment of exposureSecure record, structured interview by healthcare practitionerSecure administrative health record, read codes for midlife factors documented between aged 30 and 65 years within years 1966–2009+Anxiety history from medical history section of medical record+
 Same method of ascertainment for cases and controlsYesYes; review of risk factor read codes+Yes; review of medical history+
 Non-response rateSimilar for both cases and controlsNRNR
Total score78
  • +/− represents whether individual criterion within the subsection was fulfilled, two symbols indicate that two criteria were assessed within the subsection.

  • AD, Alzheimer’s disease; AF, atrial fibrillation; APOE, apolipoprotein E; CVD, cerebrovascular disease; DLB, dementia with Lewy bodies; IHD, ischemic heart disease; NR, not recorded.