Table 3. Multivariate analysis.
| A) Effect of caseload on progression-free survival (PFS) | ||||||
| Factor | p | Hazard ratio (95% CI) | ||||
| Caseload | continuous (per 100 pts.)* | 0.176 | 0.93 (0.84–1.04) | |||
| Sex | male | < .0001 | 1.29 (1.14–1.46) | |||
| Age at diagnosis | continuous (per year older) | < .0001 | 1.03 (1.02–1.03) | |||
| Stage (German Hodgkin Study Group [GHSG]) | intermediate + advanced | 0.0003 | 2.11 (1.40–3.17) | |||
| only advanced | < .0001 | 1.95 (1.64–2.31) | ||||
| Treatment | without BEACOPP chemotherapy protocol | < .0001 | 1.98 (1.62–2.41) | |||
| radiotherapy only | < .0001 | 3.12 (2.05–4.75) | ||||
| B symptoms | present | 0.0003 | 1.32 (1.13–1.53) | |||
| Generation | G2 | 0.200 | 1.10 (0.95–1.27) | |||
| Unobserved heterogeneity of centers (frailty) | 0.380 | |||||
| B) Effect of type of center on progression-free survival (PFS) | ||||||
| Factor | p | Hazard ratio (95% CI) | ||||
| Type of center | non-university hospital | 0.194 | 0.92 (0.81–1.05) | |||
| hematology-oncology practice | 0.283 | 1.16 (0.89–1.51) | ||||
| Sex | male | < .0001 | 1.29 (1.14–1.47) | |||
| Age at diagnosis | continuous (per year older) | < .0001 | 1.03 (1.02–1.03] | |||
| Stage (German Hodgkin Study Group [GHSG]) | intermediate + advanced | 0.0004 | 2.09 (1.39–3.14) | |||
| only advanced | < .0001 | 1.95 (1.64–2.31) | ||||
| Treatment | without BEACOPP chemotherapy protocol | < .0001 | 1.98 (1.62–2.41) | |||
| radiotherapy only | < .0001 | 3.01 (2.03–4.73) | ||||
| B symptoms | present | 0.0003 | 1.32 (1.14–1.53) | |||
| Generation | G2 | 0.236 | 1.09 (0.94–1.26) | |||
| Unobserved heterogeneity of centers (frailty) | 0.380 | |||||
*The hazard ratio here denotes the ratio of risk per 100 additionally treated patients.Multivariate analysis of G2 and G3 overall, with estimation of unobserved heterogeneity of centers; testing of the effects of caseload (A) and type of center (B) on progression-free survival (PFS) with relevant confounders. The factors expected to be associated with significantly worse PFS were male sex, older age, advanced stage of disease, presence of B symptoms, treatment in an early trial generation (G2), and less up-to-date type of treatment (without BEACOPP chemotherapy protocol, or with radiotherapy only). There was no independent prognostic effect of centers after adjustment for these factors; nor did unobserved heterogeneity of the centers play any significant role in PFS.