Adjusted differences in means in average PSI-4-SF and SF-12v1 scores between the groups of parents
| n/N* | Unadjusted sample mean | (95% CI) | Adjusted† sample mean | (95% CI) | Adjusted† difference in means | (95% CI) | P value‡ | |
| PSI-4-SF | ||||||||
| Total stress | ||||||||
| EP | 158/175 | 73.8 | (69.6 to 77.9) | 73.6 | (69.9 to 77.2) | 14.2 | (8.5 to 19.9) | <0.001 |
| Control | 112/125 | 58.6 | (55.4 to 61.8) | 59.4 | (55.1 to 63.6) | |||
| Parental distress | ||||||||
| EP | 161/175 | 24.1 | (22.6 to 25.6) | 23.9 | (22.5 to 25.2) | 2.8 | (0.7 to 5.0) | 0.03 |
| Control | 112/125 | 20.9 | (19.6 to 22.2) | 21.0 | (19.4 to 22.6) | |||
| Parent–child dysfunctional interaction | ||||||||
| EP | 161/175 | 23.3 | (22.0 to 24.7) | 23.3 | (22.0 to 24.5) | 4.6 | (2.7 to 6.5) | <0.001 |
| Control | 112/125 | 18.3 | (17.2 to 19.4) | 18.6 | (17.2 to 20.0) | |||
| Difficult child | ||||||||
| EP | 161/175 | 26.4 | (24.7 to 28.0) | 26.3 | (24.9 to 27.8) | 6.8 | (4.5 to 9.0) | <0.001 |
| Control | 112/125 | 19.4 | (18.2 to 20.6) | 19.6 | (17.9 to 21.3) | |||
| Total stress | ||||||||
| EP | 93/97 | 67.2 | (61.9 to 72.4) | 67.6 | (63.2 to 72.1) | 8.6 | (2.5 to 14.8) | 0.006 |
| Control | 109/121 | 58.5 | (55.2 to 61.7) | 58.9 | (54.8 to 63.0) | |||
| Parental distress | ||||||||
| EP | 94/97 | 21.8 | (20.0 to 23.6) | 21.7 | (20.1 to 23.4) | 0.8 | (–1.5 to 3.1) | >0.99 |
| Control | 109/121 | 20.9 | (19.5 to 22.3) | 21.0 | (19.4 to 22.5) | |||
| Parent–child dysfunctional interaction | ||||||||
| EP | 93/97 | 21.4 | (19.5 to 23.2) | 21.5 | (19.9 to 23.0) | 3.0 | (0.8 to 5.1) | 0.021 |
| Control | 109/121 | 18.3 | (17.1 to 19.4) | 18.5 | (17.0 to 19.9) | |||
| Difficult child | ||||||||
| EP | 94/97 | 24.2 | (22.0 to 26.3) | 24.4 | (22.7 to 26.2) | 5.0 | (2.6 to 7.5) | <0.001 |
| Control | 109/121 | 19.3 | (18.1 to 20.5) | 19.4 | (17.7 to 21.0) | |||
| SF-12v1 | ||||||||
| Physical Component Summary score (PCS-12) | ||||||||
| EP | 148/163 | 50.8 | (49.3 to 52.3) | 51.0 | (49.6 to 52.4) | 1.5 | (–3.7 to 0.7) | 0.18 |
| Control | 107/125 | 52.4 | (50.8 to 53.9) | 52.4 | (50.8 to 54.1) | |||
| Mental Component Summary score (MCS-12) | ||||||||
| EP | 148/163 | 49.4 | (47.8 to 50.9) | 49.3 | (47.9 to 50.7) | 1.3 | (–3.5 to 0.9) | 0.24 |
| Control | 107/125 | 50.7 | (49.2 to 52.2) | 50.6 | (48.9 to 52.3) | |||
| SF-12v1: restricted to singletons with no/mild impairment | ||||||||
| Physical Component Summary score (PCS-12) | ||||||||
| EP | 91/97 | 50.9 | (48.9 to 53.0) | 50.8 | (49.0 to 52.6) | 1.9 | (–4.4 to 0.6) | 0.14 |
| Control | 104/121 | 52.3 | (50.7 to 53.9) | 52.7 | (51.0 to 54.4) | |||
| Mental Component Summary score (MCS-12) | ||||||||
| EP | 91/97 | 51.4 | (49.8 to 53.1) | 51.1 | (49.5 to 52.8) | 0.6 | (–1.6 to 2.9) | 0.57 |
| Control | 104/121 | 50.8 | (49.2 to 52.3) | 50.5 | (49.0 to 52.0) | |||
Bold p value indicates a priori defined statistical significance (p<0.05).
*Those parents with complete set of data/all parents who returned their Parent Questionnaires at 11 years.
†Adjusted for child age, child male sex, parent age, parent ethnicity, the Index of Multiple Deprivation16 decile at 11 years, interaction of child age and birth status if present and family as a random effect if applicable.
‡Multiple linear regression with Bonferroni correction (p values multiplied by 3; Total Stress Score not corrected).
EP, extremely preterm; PSI-4-SF, Parenting Stress Index-Short Form 4th Edition.