Schmand 2012.
| Study characteristics | |||
| Patient sampling | 175 MCI participants’ data, available for all measures of interest, were used from ADNI, a multicentre project with approximately 50 medical centre and university sites across the United States and Canada. Sample procedure was not described for the study participants. Exclusion criteria: people who used antidepressant medications with anti‐cholinergic properties, or those who used drugs with narcotic properties were excluded, but use of oestrogens, cholinesterase inhibitors, or vitamin E was allowed if the dose remained stable. |
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| Patient characteristics and setting | 89 MCI ADNI participants diagnosed by the Petersen 2010 criteria who had a ¹⁸F‐FDG scan at baseline. Demographic data reported on total sample (175 MCI). Gender: converters: 31 women, 50 men; non‐converters: 30 women, 64 men Age: converters: 74.4 ± 7.4; non‐converters: 74.1 ± 7.6 APOEɛ4: not reported MMSE: converters: 26.6 ± 1.8; non‐converters: 27.2 ± 1.7 Education: converters: 15.6 ± 3.0; non‐converters: 15.8 ± 3.9 Sources of referral: not reported Sources of recruitment: multicenter |
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| Index tests | ¹⁸F‐FDG PET scan Using ¹⁸F‐FDG acquired, controlled, and analysed according to the ADNI protocol, ROI approaches (UC Berkeley) resulted in a set of 5 regions located in right and left angular gyri, bilateral posterior cingulate gyrus, and left middle/inferior temporal gyrus. Because these ROIs were highly correlated (Jagust 2010), we averaged them across participants. This composite ROI was used in the present analyses. Threshold: was based on the predicted probability of conversion to dementia as obtained from a logistic regression analysis with conversion as dependent variable and the rCGM of the ROI, described in the paper as the predictor. If this predicted probability was > 0.5, the ¹⁸F‐FDG was considered positive. This corresponds to a rCGM value of < 1.20; prespecified (Dr Schmand email on 13th August 2013). Index test was conducted before follow‐up. |
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| Target condition and reference standard(s) | Target condition: conversion from MCI to Alzheimer's disease dementia Reference standard: NINCDS/ADRDA criteria of probable ADD (including a MMSE score between 20 and 26, and a CDR score of at least 0.5). Unclear whether clinicians conducting follow‐up were aware of the ¹⁸F‐FDG results. |
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| Flow and timing |
Duration of follow‐up: mean: 2.7 ± 0.9 years; range: 0.5 ‐ 4.6 years Information from the author: At baseline: 18 participants with ¹⁸F‐FDG test positive tests; 71 participants with ¹⁸F‐FDG negative tests At follow‐up: 18 with abnormal ¹⁸F‐FDG PET scan: 9 MCI‐converters (MCI‐ADD) and 9 MCI‐non‐converters (MCI‐MCI); 71 with normal ¹⁸F‐FDG PET scan: 29 MCI‐converters (MCI‐ADD) and 42 MCI‐non‐converters (MCI‐MCI) Number included in analysis: 98 TP = 9; FP = 9; FN = 29; TN = 42 Loss to follow‐up: none |
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| Comparative | |||
| Notes | We contacted the trial investigators contacted who provided relevant data tor the 2 x 2 table to be completed (email on 13th August 2013) | ||
| Methodological quality | |||
| Item | Authors' judgement | Risk of bias | Applicability concerns |
| DOMAIN 1: Patient Selection | |||
| Was a consecutive or random sample of patients enrolled? | Unclear | ||
| Was a case‐control design avoided? | Yes | ||
| Did the study avoid inappropriate exclusions? | Yes | ||
| Unclear | Low | ||
| DOMAIN 2: Index Test All tests | |||
| Were the index test results interpreted without knowledge of the results of the reference standard? | Yes | ||
| If a threshold was used, was it pre‐specified? | Yes | ||
| Low | Low | ||
| DOMAIN 3: Reference Standard | |||
| Is the reference standards likely to correctly classify the target condition? | Yes | ||
| Were the reference standard results interpreted without knowledge of the results of the index tests? | Unclear | ||
| Unclear | Low | ||
| DOMAIN 4: Flow and Timing | |||
| Was there an appropriate interval between index test and reference standard? | Yes | ||
| Did all patients receive the same reference standard? | Yes | ||
| Were all patients included in the analysis? | Yes | ||
| Low | |||
AD: Alzheimer's disease ADAS: Alzheimer's Disease Assessment Scale ADD: Alzheimer's disease dementia APOE Ԑ4: apolipoprotein ϵ4 allele gene status CDR: clinical dementia rating FN: false negatives FP: false positives FTD: fronto‐temporal dementia IMI: isolated memory impairment LBD: Lewy body dementia MCI: mild cognitive impairment MCI‐ADD: People with MCI converted to ADD) (MCI converters) MCI‐MCI: People with stable MCI (MCI non‐converters) MCI‐NC: People with stable MCI (MCI non‐converters) MMSE: mini‐mental state examination aMCI: amnestic MCI sna‐MCI: single‐non‐amnestic MCI P‐MCI: progressive MCI ROI: region of interest S‐MCI: stable MCI SUVr: standardised uptake value ratio
SVM: support vector machine NPV: negative predictive value PPV: positive predictive value TN: true negatives TP: true positives