Table 3.
Results of secondary analysis that used hierarchical multiple linear regression to assess the proportion of variance in objective cognitive impairment (Cogstate results) explained by demographic, medical, and psychological characteristics; appropriate statistics are given for each model. Additionally, non-standardized regression coefficients and p-values are given for each variable (coefficients of variables with p-values < 0.05 are in bold).
| Model statistics | Model 1a | Model 2b | Model 3c | |||
|---|---|---|---|---|---|---|
| R2 | 0.10 | 0.15 | 0.19 | |||
| R2 change from previous model | - | 0.05 | 0.04 | |||
| p-value of LRT compared to previous model | - | 0.07 | 0.08 | |||
| Model variables | Coeff. (95% CI) |
p-value | Coeff. (95% CI) |
p-value | Coeff. (95% CI) |
p-value |
| Intercept | −0.63 (−1.30, 0.05) | 0.07 | −0.78 (−1.50, −0.06) | 0.03 | −0.76 (−1.87, 0.35) | 0.18 |
| Demographics | ||||||
| Age (years) | 0.02 (0.01, 0.02) | 0.0001 | 0.02 (0.01, 0.02) | <0.0001 | 0.02 (0.01, 0.03) | <0.0001 |
| Married/de facto relationship | −0.04 (−0.25, 0.17) | 0.71 | −0.05 (−0.26, 0.17) | 0.65 | 0.04 (−0.27, 0.18) | 0.70 |
| Education (years) | −0.01 (−0.04, 0.02) | 0.41 | −0.01 (−0.04, 0.02) | 0.36 | −0.01 (−0.04, 0.01) | 0.34 |
| Smoking history | ||||||
| Never (reference) | - | - | - | - | ||
| Previous | −0.13 (−0.28, 0.02) | 0.09 | −0.15 (−0.30, −0.01) | 0.04 | −0.20 (−0.35, −0.05) | 0.01 |
| Current | −0.03 (−0.43, 0.37) | 0.89 | −0.01 (−0.41, 0.38) | 0.95 | −0.07 (−0.47, 0.33) | 0.73 |
| Previous neurological problems | −0.02 (−0.20, 0.16) | 0.83 | −0.02 (−0.20, 0.15) | 0.79 | −0.05 (−0.23, 0.13) | 0.59 |
| Ever used antidepressants | 0.09 (−0.05, 0.24) | 0.20 | 0.11 (−0.03, 0.25) | 0.12 | 0.08 (−0.08, 0.22) | 0.31 |
| Medical characteristics | ||||||
| Tumor stage | ||||||
| I or II (reference) | - | - | - | - | ||
| III | −0.08 (−0.29, 0.13) | 0.45 | −0.09 (−0.30, 0.12) | 0.42 | ||
| Unknown | −0.08 (−0.25, 0.08) | 0.32 | −0.08 (−0.24, 0.09) | 0.36 | ||
| Hormone therapy | ||||||
| None (reference) | - | - | - | - | ||
| Tamoxifen, Letrozole, or Anastrozole | 0.12 (−0.04, 0.28) | 0.13 | 0.15 (−0.01, 0.31) | 0.07 | ||
| Other | −0.11 (−0.46, 0.24) | 0.54 | −0.05 (−0.39, 0.30) | 0.80 | ||
| # of chemotherapy cycles | 0.03 (0.00, 0.05) | 0.02 | 0.03 (0.005, 0.052) | 0.02 | ||
| Time since completion of chemotherapy (months) | −0.002 (−0.007, 0.003) | 0.40 | −0.001 (−0.006, 0.004) | 0.80 | ||
| Psychological characteristics | ||||||
| Fatigue (FACT-F) | 0.003 (−0.005, 0.012) | 0.44 | ||||
| Anxiety and depression (GHQ) | 0.01 (−0.003, 0.031) | 0.10 | ||||
| Stress (PSS) | −0.02 (−0.04, 0.005) | 0.12 | ||||
| Perceived cognitive abilities (FACT-COG PCA) | −0.01 (−0.03, 0.01) | 0.17 | ||||
| Comments from others (FACT-COG comments) | 0.01 (−0.02, 0.03) | 0.53 | ||||
| Cognitive quality of life (FACT-COG QOL) | 0.01 (−0.02, 0.04) | 0.48 | ||||
Model 1: demographics only
Model 2: demographics + medical
Model 3: demographics + medical + psychological
Coeff.: regression coefficient; CI: confidence interval; LRT: likelihood ratio test; FACT-F: Functional Assessment of Cancer Therapy – Fatigue; GHQ: General Health Questionnaire; PSS: Perceived Stress Scale; FACT-COG: Functional Assessment of Cancer Therapy Cognitive Function questionnaire.
Note: all three models were run on the same 206 observations, where Cogstate results and all covariates for the fullest model (Model 3) were not missing.