Table 5.
Calibration of PROSTQA Models in the CaPSURE Cohort: Comparison of Model-Predicted Probabilities of Functional Erections Suitable for Intercourse to Observed Proportions of Men Reporting Functional Erections 2 Years After Treatmenta
| Quintiles (Ranges) of PROSTQA Model–Predicted Probabilities |
No. | Functional Erections 2 y After Treatmentb |
||
|---|---|---|---|---|
| Mean PROSTQA Model–Predicted Probabilities |
Observed Proportion |
|||
| Prostatectomy | ||||
| 1st (0.001–0.030) | 216 | 0.01 | 0.04 | |
| 2nd (0.031–0.114) | 215 | 0.07 | 0.08 | |
| 3rd (0.115–0.246) | 215 | 0.18 | 0.20 | |
| 4th (0.247–0.403) | 219 | 0.32 | 0.36 | |
| 5th (0.404–0.760) | 212 | 0.52 | 0.48 | |
| All | 1077 | 0.22 | 0.23 | |
| External radiotherapy | ||||
| 1st (0.005–0.013) | 47 | 0.01 | 0.04 | |
| 2nd (0.014–0.031) | 50 | 0.02 | 0.00 | |
| 3rd (0.032–0.089) | 44 | 0.05 | 0.02 | |
| 4th (0.090–0.251) | 47 | 0.16 | 0.13 | |
| 5th (0.252–0.789) | 47 | 0.43 | 0.45 | |
| All | 235 | 0.13 | 0.15 | |
| Brachytherapy | ||||
| 1st (0.005–0.006) | 69 | 0.003 | 0.014 | |
| 2nd (0.007–0.035) | 68 | 0.02 | 0.04 | |
| 3rd (0.036–0.148) | 68 | 0.09 | 0.18 | |
| 4th (0.149–0.469) | 69 | 0.30 | 0.36 | |
| 5th (0.470–0.950) | 69 | 0.68 | 0.78 | |
| All | 343 | 0.22 | 0.27 | |
Abbreviations: CaPSURE, Cancer of the Prostate Strategic Urologic Research Endeavor; PROSTQA, Prostate Cancer Outcomes and Satisfaction With Treatment Quality Assessment.
Characteristics that differed between CaPSURE respondents and nonrespondents included race/ethnicity, relationship status, education, Gleason score at biopsy, and nerve sparing. Calibration was assessed within quintiles (fifths) of the distribution of model-predicted probabilities.
Individual model-predicted probabilities were calculated using the inverse logistic function {exp[X′ β]/[1 + exp(X′ β)]}, where X′ β is the sum with X representing individual characteristics observed and β representing the associated model parameter estimates for the individual characteristics in Table 1.