Generalised estimating equations (GEE) model 2 to evaluate the effect of frequent exacerbations during follow up on five repeated measures of the SGRQ total score* in patients with severe COPD
| Mean (SE) coefficient | 95% CI | p value | Mean (SE) coefficient | 95% CI | p value | |
|---|---|---|---|---|---|---|
| *Coefficients of the model were adjusted for the other variables in the table as well as for age, number of coexisting chronic conditions, body mass index, cumulative tobacco consumption, and years of evolution of COPD. | ||||||
| †For differences within patients, coefficients of interaction terms between each factor and repeated measures were calculated as total SGRQ score changes by year. | ||||||
| ‡Dyspnoea groups were transformed into three variables (I, II and III) using the deviations from the means coding. | ||||||
| Constant | 41.60 (3.40) | 34.94 to 48.26 | 0.000 | |||
| Season | ||||||
| Winter | − | − | − | |||
| Summer | −2.97 (0.58) | −4.12 to −1.83 | 0.000 | |||
| Annual rate of change | −1.75 (1.45) | −4.59 to 1.08 | 0.225 | |||
| Differences between patients | Differences within patients† | |||||
| Factors | ||||||
| Exacerbations | ||||||
| <3 | – | – | – | – | – | – |
| ⩾3 | 2.96 (1.96) | −1.14 to 6.52 | 0.169 | −0.42 (0.84) | −2.06 to 1.22 | 0.618 |
| Hospital admission | ||||||
| No | – | – | – | – | – | – |
| Yes | 5.53 (2.04) | 1.52 to 9.53 | 0.007 | 1.61 (0.87) | −0.10 to 3.32 | 0.066 |
| Dyspnoea‡ | ||||||
| I | −6.20 (3.52) | −13.10 to 0.69 | 0.078 | 1.30 (1.50) | −1.64 to 4.24 | 0.387 |
| II | 5.23 (3.40) | −1.44 to 11.90 | 0.124 | −0.42 (1.45) | −3.27 to 2.42 | 0.770 |
| III | 19.71 (3.52) | 12.81 to 26.62 | 0.000 | −2.43 (1.51) | −5.38 to 0.52 | 0.106 |