Skip to main content
. 2022 Apr 1;12:136. doi: 10.1038/s41398-022-01897-y

Table 3.

Moderator analyses.

Moderators TST WASO Number of awakenings SE SL N1% N2% SWS% REM% REML REMD
Sex (male%) No. of comparisons 22 16 15 20 19 18 19 24 24 22 6
No. of AD/Controls 634/650 540/541 383/415 579/594 578/600 494/485 541/529 634/649 658/701 599/636 119/155
Point estimate 0.477 0.793 1.354 1.651 −1.290 −3.561 −1.189 0.378 −0.557 0.202 −1.077
SE 1.319 2.410 0.991 1.836 0.502 2.168 1.626 0.989 1.270 0.743 0.550
P 0.718 0.742 0.172 0.369 0.010 0.100 0.464 0.702 0.661 0.786 0.0503
Mean age No. of comparisons 22 16 15 19 19 18 19 24 24 22 6
No. of AD/Controls 636/651 540/541 383/415 571/585 580/601 496/486 543/530 636/650 660/702 601/637 121/156
Point estimate −0.019 −0.071 −0.023 −0.001 0.048 0.041 0.004 −0.002 0.028 0.004 0.036
SE 0.033 0.056 0.041 0.053 0.018 0.057 0.041 0.037 0.049 0.027 0.024
P 0.567 0.206 0.575 0.983 0.008 0.470 0.922 0.952 0.570 0.882 0.133
Education (years) No. of comparisons 8 8 9 7 6 7 8 12 11 8 –
No. of AD/Controls 322/318 322/318 289/310 278/273 287283 256/254 303/298 391/409 366/384 287/304 –
Point estimate 0.053 0.019 0.151 0.030 −0.035 −0.473 −0.200 0.080 0.023 0.032 –
SE 0.088 0.079 0.086 0.098 0.038 0.059 0.119 0.054 0.078 0.046 –
P 0.542 0.811 0.079 0.762 0.359 <0.001 0.094 0.138 0.768 0.492 –
MMSE score No. of comparisons 21 16 15 18 18 16 17 22 23 21 6
No. of AD/Controls 621/636 540/541 383/415 556/570 565/586 456/446 503/490 596/610 645/687 586/622 121/156
Point estimate 0.044 0.023 −0.022 −0.027 0.027 −0.011 0.011 0.049 0.067 −0.026 0.011
SE 0.045 0.057 0.025 0.067 0.021 0.080 0.054 0.028 0.037 0.022 0.030
P 0.330 0.681 0.370 0.693 0.202 0.888 0.842 0.075 0.071 0.229 0.714
Medication free
Not reported No. of comparisons 1 – 3 – 1 1 1 4 4 4 1
No. of AD/Controls 10/10 – 44/66 – 10/10 10/10 10/10 54/76 54/76 54/76 10/10
SMD −0.062 – 0.895*** – −0.240 0.601 0.277 −1.100*** −1.375*** 0.713*** −0.749
Q 0 – 0.010 – 0 0 0 3.198 10.498* 2.654 0
I2 0 – 0 – 0 0 0 6.184 71.424 0 0
Yes No. of comparisons 22 16 12 20 19 18 19 21 21 19 6
No. of AD/Controls 634/650 540/541 339/349 579/594 578/600 494/485 541/529 590/583 614/635 555/570 119/155
SMD −0.616*** 0.739*** 0.471** −0.962*** 0.471*** 0.831** 0.084 −0.818*** −0.654** 0.290* −0.245
Q 101.331*** 112.309*** 47.307*** 174.611*** 27.648 186.036*** 118.443*** 120.355*** 216.640*** 66.595*** 5.472
I2 79.216 86.644 76.748 89.119 34.895 90.862 84.803 83.383 90.768 72.971 8.633
Between-group difference Q 1.404 – 2.415 – 2.431 0.199 0.162 1.196 2.737 3.531 1.094
P 0.236 – 0.120 – 0.119 0.656 0.688 0.274 0.098 0.060 0.296
Adaptation night
No No. of comparisons 6 4 3 5 3 4 5 6 6 4 –
No. of AD/Controls 113/114 93/90 46/46 102/103 67/68 61/61 108/105 113/114 113/114 78/79 –
SMD −0.526** 0.018 0.054 −0.495** 0.657*** 0.870*** −0.006 −0.635** −0.415 0.164 –
Q 7.131 0.034 3.998 1.017 0.777 4.303 15.965** 12.638* 17.452** 5.657 –
I2 29.880 0 49.979 0 0 30.280 74.946 60.438 71.350 46.972 –
Yes No. of comparisons 17 12 12 15 17 15 15 19 19 19 7
No. of AD/Controls 531/546 447/451 337/369 477/491 521/542 443/434 443/434 531/545 555/597 531/567 129/165
SMD −0.599*** 0.974*** 0.663*** −1.091*** 0.413*** 0.789** 0.119 −0.925*** −0.862*** 0.385** −0.286*
Q 95.029*** 93.838*** 44.358*** 168.870*** 28.124* 179.947*** 98.831*** 109.629*** 218.276*** 67.292*** 6.644
I2 83.163 88.278 75.202 91.710 43.110 92.220 85.834 83.581 91.754 73.251 9.698
Between-group difference Q 0.092 12.830 3.045 4.037 1.491 0.051 0.121 0.976 1.524 0.603 –
P 0.792 <0.001 0.081 0.045 0.222 0.822 0.728 0.323 0.217 0.438 –
PSG scoring methods
AASM No. of comparisons 6 5 1 5 4 5 5 5 5 6
No. of AD/Controls 182/158 165/138 11/11 171/147 151/132 162/143 162/143 162/143 162/143 182/158 –
SMD −1.108*** 1.386*** 0.774 −1.996*** 0.488** 2.156*** 0.456 −1.699** −2.170*** 0.587* –
Q 26.862*** 26.104*** 0 59.169*** 4.833 14.677** 65.047*** 49.543*** 35.402*** 18.508** –
I2 81.386 84.677 0 93.240 37.924 72.747 93.851 91.926 88.701 72.984 –
R&K No. of comparisons 17 11 14 15 16 14 15 20 20 17 7
No. of AD/Controls 462/502 375/403 372/404 408/447 437478 342/352 389/396 482/516 506/568 427/488 129/165
SMD −0.398** 0.435** 0.539** −0.597*** 0.437*** 0.301* −0.044 −0.650*** −0.385** 0.250* −0.286*
Q 41.806*** 31.063** 52.508*** 32.323** 25.181* 25.200* 44.029*** 39.866** 62.067*** 39.630** 6.644
I2 61.728 67.808 75.242 56.687 40.430 48.412 68.203 52.340 69.388 59.626 9.698
Between-group difference Q 5.190 6.250 0.249 5.964 0.074 34.444 0.843 4.129 14.221 1.719 –
P 0.023 0.012 0.618 0.015 0.786 <0.001 0.358 0.042 <0.001 0.190 –

A meta-regression or subgroup analysis (depending on whether the potential moderators were continuous or categorical variables) was conducted to determine the potential factors that could moderate heterogeneity between studies. Of which, the effects of sex, age, education, and MMSE score were explored by using a meta-regression analysis, while the effects of whether taking medication impacts sleep (Yes vs. No), adaptation night (Yes vs. No), and PSG scoring methods (AASM vs. R&K) were explored by using subgroup analysis.

AASM American Academy of Sleep Medicine, AD Alzheimer’s disease, AHI apnea-hypopnea index, Q Cochran’s Q statistic, MMSE mini-mental state examination, PSG polysomnography, REM rapid eye movement sleep, REMD REM density, REML REM latency, R&K Rechtschaffen and Kales, SMD standardized mean difference, SWS slow-wave sleep, SE sleep efficiency, SL sleep latency, TST total sleep time, WASO wake time after sleep onset.

*p < 0.05, **p < 0 .01, ***p < 0.001.