Beta-agonist type | FEV1 rate of change, mean percent predicted per year ± SE |

None | −1.470 ± 0.070 (1,594 visits) |

Beta-agonist | −1.939 ± 0.118 (962 visits) |

P < 0.001 | |

None | −1.304 ± 0.082 (1,594 visits) |

Short-acting | −1.677 ± 0.238 (391 visits) |

Both short-acting and long-acting | −0.783 ± 0.255 (349 visits) |

Long-acting | −2.443 ± 0.391 (222 visits) |

N vs. S | P = 0.1291 |

N vs. SL | P = 0.0457 |

N vs. L | P = 0.0040 |

S vs. SL | P = 0.0095 |

S vs. L | P = 0.0908 |

SL vs. L | P = 0.0003 |

With statistical correction, significant

*P*values are those less than 0.0083. L, long-acting beta-agonist; N, no beta agonist; S, short-acting beta-agonist; SL, short- and long-acting beta-agonists.