Table 2.
Case-controlled studies: Newcastle-Ottawa Scale for the assessment of quality of included case-controlled studies
| Acceptable criteria | Zilkens et al 18 | Boot et al19 | |||
| Selection | |||||
| Case definition | With independent validation | Record linkage from Western Australian Data Linkage System and Death Registry, no independent validation | − | Assessment for DLB using behavioural neurologist | + |
| Representativeness of cases | Consecutive or representative series of cases | All 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 controls | Community controls | Population 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 controls | No history of disease | Excluded 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 | |||||
| Comparability of cases and controls on basis of design and analysis | Study 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) | ++ |
| Exposure | |||||
| Ascertainment of exposure | Secure record, structured interview by healthcare practitioner | Secure 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 controls | Yes | Yes; review of risk factor read codes | + | Yes; review of medical history | + |
| Non-response rate | Similar for both cases and controls | NR | − | NR | − |
| Total score | 7 | 8 | |||
+/− 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.