Outcomes and subgroups | Participants (n) | Studies (n) | Mean difference (unsupervised− supervised)^{#} | LoA | 95% CI | I^{2} (%) | Anticipated impact (%)^{¶} |

FEV_{1} overall | 4517 | 17 | −106 mL | −509, 296 | −129, −84 | 95.8 | 38.9 |

Low risk of bias | 2679 | 4 | −103 mL | −444, 238 | −160, −46 | 96.2 | 38.6 |

At risk of bias | 1178 | 14 | −115 mL | −705, 475 | −154, −75 | 95.9 | 39.9 |

Same day measurements | 235 | 5 | −65 mL | −421, 292 | −129, −1 | 95.4 | 35 |

Non-same day measurements | 3520 | 11 | −144 mL | −561, 272 | −184, −105 | 95.3 | 43.8 |

Adults | 3627 | 14 | −103 mL | −517, 311 | −134, −73 | 93.6 | 38.6 |

Children | 230 | 4 | −132 mL | −410, 146 | −222, −42 | 98.2 | 42.1 |

FVC overall | 1307 | 17 | −184 mL | −1028, 660 | −253, −114 | 96 | 66.9 |

Low risk of bias | 238 | 4 | −118 mL | −886, 650 | −201, −35 | 88.5 | 65.2 |

At risk of bias | 1069 | 13 | −207 mL | −1098, 684 | −300, −114 | 96.6 | 67.7 |

Same day measurements | 106 | 2 | −14 mL | −287, 260 | −42, 15 | 0 | 63.9 |

Non-same day measurements | 1099 | 13 | −228 mL | −1239, 783 | −285, −171 | 85.3 | 68.4 |

Adults | 1215 | 16 | −198 mL | −1162, 766 | −262, −134 | 92.5 | 67.7 |

FEF_{25–75%} | 146/899 | 3 | −19 mL·s^{−1} | −497, 458 | −329, 291 | 99.7 | 41.3 |

PEF | 124/400 | 2 | −92 mL·s^{−1} | −498, 314 | −110, −74 | 0 | 38.1 |

The standard deviation was imputed for five studies so mean differences could be calculated after efforts were made to obtain data from authors [30, 37, 38, 40, 49]. LoA: limits of agreement; FEV_{1}: forced expiratory volume in 1 s; FVC: forced vital capacity; FEF_{25–75%}: forced expiratory flow at 25–75% of the FVC; PEF: peak expiratory flow. ^{#}: a negative mean difference indicates unsupervised spirometry is lower. ^{¶}: percentage of results that would probably have a difference >200 mL.