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Table 1 Characteristics of studies included in the final review

From: The prevalence of obstructive sleep apnea in mild cognitive impairment: a systematic review

Variables Groups Dlugaj et al. (2014) [24] Guarnieri et al. (2012) [26] Kim et al. (2011) [27] Osorio et al. (2015) [2] Wilson et al. (2014) [28]
Referral Population General population (HNR cohort); age 45–75 yrs. Neurology clinic; age > 60 years General practitioner clinic (Public health centre); age > 60 years Multiple clinics (ADNI cohort); age 55–90 yrs. Neurology clinic; age > 50 years
Study design Cross-sectional Cross-sectional Cross-sectional Retrospective Cohorta Cross-sectional
Study country Germany Italy South Korea USA and Canada Australia
MCI diagnosis criteria Petersen (2004) [6] Winblad (2004) [8] Winblad (2004) [8] Petersen (1999) [4] Petersen (2005) [7] Petersen (2005) [7]
OSA diagnosis method ApneaLink™ History of snoring or sleep apneas & high risk on Berlin Questionnaire PSG “Patient reported OSA, followed by physician assessment of diagnosis based on patients’ medical history” PSG
OSA diagnosis criteria AHI ≥ 15 events/hour NA AHI ≥ 5 events/hour NR AHI ≥ 5 events/hour
OSA AHI Indicesb A: ≥80%, ≥10s
H: 50–80%, ≥10s
OD: NR
NA A: ≥100%, ≥10s
H: ≥50%, ≥10s
OD: 3% (or arousal)
NR A: ≥100%, ≥10s
H: ≥50%, ≥10s
OD: 3% (or arousal)
Number of subjects MCI 230 138 30 402 37
aMCI 120 NR NR 402 10
naMCI 110 0 27
Controls 676 30 607 37
Number of males, n (%) MCI 919 (51%) 50% 9 (30%) NR
Controls 9 (30%)
Age (years), mean ± SD MCI 63.79 ± 7.45 73 ± 9c 67.97 ± 4.09 65.5 ± 9.0
Controls 67.37 ± 3.75 63.5 ± 8.7
BMI (kg/m2), mean ± SD MCI 28.06 ± 4.38 NR 24.40 ± 3.28 27.6 ± 5.5
Controls 24.49 ± 2.75 27.1 ± 4
Comorbidities (major) DM (18%), HTN (36%), CAD (7%) NR NR NR
Education (years), n (%) or mean ± SD MCI ≤10: 167 (9%); 11–13: 1002 (56%); ≥14: 624 (35%) 8.2 ± 4.2c 6.80 ± 4.67 NR
Controls 7.90 ± 5.11 NR
AHI (events/hour) MCI 11.5 ± 11.43 NR 13.41 ± 11.61 NR 16.4 ± 16d
Controls 15 ± 13.56 11.9 ± 10d
APOE positive (%) MCI 445 (25%) NR NR NR
Controls
Mini Mental Status Exam, mean ± SD MCI NR 27 ± 2c NR NR 28.1 ± 1.5
Controls 29.2 ± 1.1
  1. Abbreviations: A apnea, ADNI Alzheimer’s disease Neuroimaging Initiative, AHI apnea-hypopnea index, APOE Apolipoprotein E, BMI body mass index, CAD coronary artery disease, DM diabetes mellitus, HNR Heinz Nixdorf Recall, HTN hypertension, H hypopnea, MCI mild cognitive impairment, NA not applicable, NR not reported, OD oxygen desaturation, OSA obstructive sleep apnea, PSG polysomnography, SD standard deviation
  2. aData to calculate prevalence and/or odds ratio were provided by the study authors and were taken from baseline measurements of OSA and MCI (cross-sectional)
  3. bThe percentage drop of airflow from baseline for 10 s or more with or without oxygen desaturation
  4. cValues estimated from a bar-graph
  5. dAHI data was available on 24 out of the 37 subjects with MCI and 25 out of the 37 control subjects