Table 1.
Participant and nonparticipant characteristics
| Nonparticipants* | Participants† | P‡ | Intervention | Control | P‡ | |
|---|---|---|---|---|---|---|
| No. | 2952 | 255 | 133 | 122 | ||
| Stage (0–III), % | .86 | .23 | ||||
| 0 | 0.3 | 0.0 | – | 0.0 | 0.0 | – |
| I | 25.3 | 25.9 | – | 26.4 | 25.2 | – |
| II | 44.3 | 46.1 | – | 41.6 | 51.4 | – |
| III | 29.4 | 27.6 | – | 32.0 | 22.4 | – |
| Tumor size, mean (SD), mm | 19.4 (29.1) | 19.6 (13.5) | .93 | 20.5 (13.1) | 18.6 (13.8) | .29 |
| ER status, mean (SD), % pos. cells | 77.1 (38.0) | 80.7 (35.1) | .12 | 81.6 (34.7) | 79.6 (35.7) | .66 |
| Lymph node positive, % | 39.5 | 45.8 | .06 | 47.6 | 43.6 | .54 |
| Premenopausal, % | 51.5 | 62.0 | .002‖ | 59.2 | 64.7 | .37 |
| Mastectomy, % | 29.2 | 32.8 | .23 | 31.6 | 33.9 | .70 |
| Chemotherapy, % | 47.9 | 56.7 | .03¶ | 50.4 | 63.6 | .07 |
| Radiotherapy, % | 74.5 | 74.0 | .92 | 74.5 | 85.9 | .13 |
| Endocrine therapy, % | 76.0 | 77.6 | .21 | 77.4 | 81.0 | .45 |
| Age at surgery, mean (SD)§ | 52.3 (11.2) | 50.2 (8.8) | <.001‖ | 50.3 (8.8) | 50.1 (8.9) | .89 |
| Age group, y | <.001 | .95 | ||||
| 18–40 | 16.3 | 14.6 | - | 12.8 | 14.9 | – |
| 41–50 | 32.9 | 45.3 | - | 46.6 | 46.3 | – |
| 51–60 | 25.0 | 24.7 | - | 25.6 | 23.1 | – |
| 61–75 | 25.8 | 15.4 | - | 15.0 | 15.7 | – |
| Age at inclusion, mean (SD)§ | – | 53.1 (8.8) | – | 53.2 (8.8) | 52.9 (8.9) | .81 |
| Time from surgery, mean (SD), y | – | 2.9 (2.9) | – | 2.9 (1.8) | 2.9 (3.8) | .98 |
| Married/partnered, % | – | 79.6 | – | 78.2 | 81.1 | .56 |
| Education | .24 | |||||
| Lower (<2 y of higher ed.) | – | 23.9 | – | 22.3 | 25.7 | – |
| Medium (2–4 y of higher ed.) | – | 57.8 | – | 55.4 | 60.6 | – |
| Higher (≥5 y of higher ed.) | – | 18.3 | – | 22.3 | 13.8 | – |
| Body mass index, mean (SD), kg/m2 | – | 25.7 (4.8) | – | 25.3 (4.2) | 26.1 (5.3) | .17 |
| Alcohol, mean (SD), drinks/wk | – | 7.2 (5.3) | – | 6.9 (5.2) | 7.7 (5.3) | .32 |
| Smoker, % | – | 8.2 | – | 8.3 | 8.2 | .98 |
| Working, % | – | 76.1 | – | 77.4 | 74.6 | .59 |
| Work type: day, evening, shift, % | – | 91.4, 2.3, 6.3 | – | 90.0, 2.2, 7.8 | 92.9, 2.4, 4.8 | .72 |
| Insomnia duration, mean (SD), y | – | 3.4 (2.7) | – | 3.3 (2.8) | 3.4 (2.7) | .77 |
| Sleep medication, last 30 d, % | – | 15.3 | – | 15.8 | 14.8 | .82 |
| Sleep aids: herbal supplements, % | – | 10.6 | – | 13.5 | 7.4 | .11 |
| Sleep aids: relaxation, % | – | 46.3 | – | 46.6 | 45.9 | .91 |
| Sleep aids: other, % | – | 50.2 | – | 51.1 | 49.2 | .76 |
| Morningness (rMEQ), mean (SD)# | – | 16.7 (3.5) | – | 16.7 (3.6) | 16.8 (3.5) | .86 |
| Motivation and expectancy, mean (SD)** | – | 10.6 (2.5) | – | 10.6 (2.6) | 10.5 (2.5) | .85 |
Includes nonresponders, decliners, and excluded. ER = estrogen receptor; rMEQ = reduced Morningness-Eveningness Questionnaire.
Participants who consented and completed baseline measures.
t test for independent samples or chi-square tests (two-sided), as appropriate, after adjusting for multiple comparisons with the Benjamini-Hochberg procedure (35).
Age at surgery differs from age at inclusion (mean = 2.9 years later).
When entering participants vs nonparticipants as the dependent variable and age and menopausal status (pre/post) as independent variables in a logistic regression, neither remained statistically significant (P = .37 and .22).
When adjusting for multiple comparisons (35), chemotherapy did not reach the adjusted statistical significance level (P < .02).
reduced Morningness-Eveningness Questionnaire (27).
Five-item ad hoc scale.