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Authors Alemozaffar M, Regan MM, Cooperberg MR, et al
Review Date Oct 2011
Citation JAMA 2011;306(11):1205-1214 (also see editorial on page 1258)
A new area of research focusing on ‘patient-centred outcomes’ asks questions about what outcomes patients can expect from various medical interventions given their personal characteristics, conditions and preferences. Prostate cancer treatments have varying risks associated with them and choices about treatments may be influenced by possible adverse outcomes such as erectile dysfunction. Sexual function is the health-related quality of life (HRQOL) domain most commonly impaired after prostate cancer treatment. However, validated tools to enable personalised prediction of erectile dysfunction after prostate cancer treatment are lacking
To predict long-term erectile function following prostate cancer treatment based on individual patient and treatment characteristics.
Pre-treatment patient characteristics, sexual HRQOL, and treatment details measured in a longitudinal academic multi-centre cohort (Prostate Cancer Outcomes and Satisfaction With Treatment Quality Assessment; enrolled from 2003 through 2006), were used to develop models predicting erectile function two years after treatment. A community-based cohort (community-based Cancer of the Prostate Strategic Urologic Research Endeavor [CaPSURE]; enrolled 1995 through 2007) externally validated model performance.
Patients in US academic and community-based practices whose HRQOL was measured pre-treatment (N = 1201) underwent follow-up after prostatectomy, external radiotherapy, or brachytherapy for prostate cancer.
Sexual outcomes among men completing two years follow-up (n = 1027; 86%) were used to develop models predicting erectile function that were externally validated among 1913 patients in a community-based cohort. The main outcome measure was patient-reported functional erections suitable for intercourse two years following prostate cancer treatment.
Two years after prostate cancer treatment, 368 (37% [95% CI, 34%-40%]) of all patients and 335 (48% [95% CI, 45%-52%]) of those with functional erections prior to treatment reported functional erections; 531 (53% [95% CI, 50%-56%]) of patients without penile prostheses reported use of medications or other devices for erectile dysfunction.
Pre-treatment sexual HRQOL score, age, serum prostate-specific antigen level, race/ethnicity, body mass index, and intended treatment details were associated with functional erections two years after treatment.
Multivariable logistic regression models predicting erectile function estimated two-year function probabilities from as low as 10% or less to as high as 70% or greater depending on the individual’s pre-treatment patient characteristics and treatment details. The models performed well in predicting erections in external validation among CaPSURE cohort patients (areas under the receiver operating characteristic curve, 0.77 [95% CI, 0.74-0.80] for prostatectomy; 0.87 [95% CI, 0.80-0.94] for external radiotherapy; and 0.90 [95% CI, 0.85-0.95] for brachytherapy).
Stratification by pre-treatment patient characteristics and treatment details enables prediction of erectile function two years after prostatectomy, external radiotherapy, or brachytherapy for prostate cancer.
Points to Note
- The study has provided a good model for using baseline patient characteristics to predict patient outcomes, in this case with respect to erectile function. However, the study has some limitations.
- This is an observational study with a possibility of selection bias by mode of treatment. Therefore, the predictive models are best used to guide outcome expectation within treatment groups, rather than to determine which treatment is superior.
- A two-year follow-up period gives a good indication of long-term outcomes but there is a possibility of further improvement or deterioration of sexual function after this time.
- There is inherent uncertainty in the models that would need to be explained to patients if used in clinical practice so that they are not given unrealistic expectations of treatment outcomes.
- Treatment outcomes will change over time – for example nerve-sparing surgery may have better outcomes now than at the time this study was conducted. Also, surgery outcomes are likely to be surgeon-dependent.