Validation of an Age-adjusted Prostate Cancer–Specific Comorbidity Index

Validation of the prostate cancer comorbidity index in predicting cause-specific mortality in men undergoing radical prostatectomy

PURPOSE

Accurate prediction of competing risks of mortality remains a key component of prostate cancer treatment decision-making. We sought to validate the Prostate Cancer Comorbidity Index (PCCI) score for predicting other-cause mortality (OCM) and cancer outcomes in men undergoing radical prostatectomy (RP).

MATERIALS AND METHODS

We sampled 4857 men with prostate cancer treated with RP in the VA from 2000-2018. Risks of OCM, 90-day all-cause mortality (ACM), prostate cancer-specific mortality, metastasis, and biochemical recurrence by PCCI score were assessed using Cox proportional hazards and logistic regression. We compared prediction of 90-day ACM between PCCI and the American Society of Anesthesiology (ASA) score, a validated predictor of short-term mortality.

RESULTS

Over median follow-up of 6.7 years (IQR 3.7-10.3), there was a stepwise increase in risk of OCM with higher PCCI score, with hazards (95%CI) of 1.53 (1.14-2.04), 2.11 (1.55-2.88), 2.36 (1.68-3.31), 3.61 (2.61-4.98), and 4.99 (3.58-6.96) for PCCI 1-2, 3-4, 5-6, 7-9, and 10 + (vs. 0), respectively. Projected 10-year cumulative incidence of OCM was 8%, 12%, 16%, 19%, 26%, and 32% for scores of 0, 1-2, 3-4, 5-6, 7-9, and 10+ , respectively. Men with PCCI 7+ had greater odds of 90-day ACM (OR 3.48, 95%CI 1.26-9.63) while men with higher ASA did not. Higher PCCI score was associated with worse cancer outcomes, with the highest categories driving the associations.

CONCLUSIONS

The PCCI is a robust measure of short- and long-term OCM after RP, validated for use in clinical care and health services research focusing on surgical patient populations.

Development of comorbidity score for patients undergoing major surgery

OBJECTIVE

To develop and validate a claims-based comorbidity score for patients undergoing major surgery, and compare its performance with established comorbidity scores.

DATA SOURCE

Five percent Medicare data from 2007 to 2014.

STUDY DESIGN

Retrospective cohort study of patients aged ≥65 years undergoing six major operations (N = 99 250).

DATA COLLECTION

One-year mortality was the primary outcome. Secondary outcomes were hospital mortality, 30-day mortality, 30-day readmission, and length of stay. The comorbidity score was developed in the derivation cohort (70 percent sample) using logistic regression model. The comorbidity score was calibrated and validated in the validation cohort (30 percent sample), and compared against the Charlson, Elixhauser, and Centers for Medicare and Medicaid Services Hierarchical Condition Categories (CMS-HCC) comorbidity scores using c-statistic, net reclassification improvement, and integrated discrimination improvement.

PRINCIPAL FINDINGS

In the validation cohort, the surgery-specific comorbidity score was well calibrated and performed better than the Charlson, Elixhauser, and CMS-HCC comorbidity scores for all outcomes; the performance was comparable to the CMS-HCC for 30-day readmission. For example, the surgery-specific comorbidity score (c-statistic = 0.792; 95% CI, 0.785-0.799) had greater discrimination than the Charlson (c-statistic = 0.747; 95% CI, 0.739-0.755), Elixhauser (c-statistic = 0.747; 95% CI, 0.735-0.755), or CMS-HCC (c-statistic = 0.755; 95% CI, 0.747-0.763) scores in predicting 1-year mortality. The net reclassification improvement and integrated discrimination improvement were greater for surgery-specific comorbidity score compared to the Charlson, Elixhauser, and CMS-HCC scores.

CONCLUSIONS

Compared to commonly used comorbidity measures, a surgery-specific comorbidity score better predicted outcomes in the surgical population.

Temporal order of cancers and mental disorders in an adult population

BACKGROUND

Population-based examination of comorbidity is an emerging field of study.

AIMS

The purpose of the present population level study is to expand our understanding of how cancer and mental illness are temporally associated.

METHOD

A sample of 83 648 056 physician billing records for 664 838 (56% female) unique individuals over the age of 18 was stratified on ages 19-49 years and 50+ years, with temporal order of mental disorder and cancer forming the basis of comparison.

RESULTS

Mental disorders preceded cancers for both genders within each age strata. The full range of cancers and mental disorders preceding or following each pivot ICD class are described in terms of frequency of diagnosis and duration in days, with specific examples illustrated.

CONCLUSIONS

The temporal comorbidity between specific cancers and mental disorders may be useful in screening or clinical planning and may represent indicators of disease mechanism that warrant further screening or investigation.

DECLARATION OF INTEREST

None.

Only <10% of Patients Selected for Radical Prostatectomy Reach the Competing Mortality Rate of the Prostate Cancer Intervention Versus Observation Trial (PIVOT)

In the Prostate Cancer Intervention Versus Observation Trial (PIVOT), surgery was not associated with lower mortality compared with observation. However, the high competing mortality rate of approximately 33% after 10 yr among the PIVOT study population has raised concerns on the generalizability of these results. We investigated 4282 patients who underwent radical prostatectomy at our institution between 1992 and 2010 to determine which subgroups harbored a competing (non-prostate cancer) mortality risk comparable to that of PIVOT and tested several combinations of higher age and comorbidities ("worst case scenarios") to identify subgroups reaching or even superseding the competing mortality rate of the PIVOT population. The competing mortality rate of PIVOT was not reached till an age-adjusted Charlson score of 5 or higher (corresponding to an age of 70-79 yr with diabetes with end-organ damage). Only 8.9% of patients belonged to this high-risk subgroup, and only small subgroups comprising 1-5% patients superseded the competing mortality rate among the PIVOT study population. This data underline that the results of PIVOT should be used with great caution to exclude candidates for radical prostatectomy with comorbidities from curative treatment. PATIENT SUMMARY: Only <10% of patients selected for radical prostatectomy reached the competing mortality rate of approximately 33% observed in the Prostate Cancer Intervention Versus Observation Trial (PIVOT). The results of PIVOT should be used with great caution to exclude patients with concomitant diseases who seem otherwise fit for radical prostatectomy from curative treatment.

Ten-year Mortality in Men With Nonmetastatic Prostate Cancer in Norway

OBJECTIVE

To provide population-based data on 10-year prostate cancer-specific mortality (PCSM), overall mortality (OM), treatment, and prognostic factors in patients with nonmetastatic prostate cancer (PCa).

MATERIALS AND METHODS

Based on data from the Norwegian Prostate Cancer Registry, we calculated 10-year PCSM and OM in 3449 patients diagnosed with nonmetastatic PCa in 2004-2005 who underwent radical prostatectomy (n = 913), radiotherapy (n = 1334), or no local treatment (n = 1202). Patients were stratified according to risk group, Gleason grade group (GGG), and Eastern Cooperative Oncology Group (ECOG) performance status. Aalen-Johansen and Kaplan-Meier estimates and proportional hazards regressions were used.

RESULTS

The 10-year PCSM rate was 8.5% (radical prostatectomy: 1.5, radiotherapy: 6.2%, no local treatment: 16.3%) and the OM rate was 25.5%. In the low-risk group, the risk of dying from other causes was 8-fold increased compared with death from PCa, the comparable factor being approximately 2 among high-risk patients. Patients with high-risk factors seemed to benefit the most from local treatment. Within each risk group, the 5 GGGs improved the prediction of PCSM. Having an ECOG performance status of ≥1 doubled the risk of PCSM compared with patients with an ECOG performance status of 0.

CONCLUSION

For all patients, the 10-year OM was about 3 times higher than PCSM, the greatest and lowest discrepancies emerging among patients with low- and high-risk tumors, respectively. The results support increased use of local treatment in high-risk patients. GGGs should be implemented in clinical practice. The role of ECOG performance status as prognostic factor has to be validated in future studies.

Predicting Competing Mortality in Patients Undergoing Radical Prostatectomy Aged 70 yr or Older

Estimating the risk of competing mortality is of importance in tailoring optimal individual management strategies in patients with early prostate cancer. Using proportional hazard models for competing risks, we determined which parameters predict competing mortality in patients selected for radical prostatectomy aged 70 yr or older and compared the prognostic impact of individual parameters with that of their younger counterparts. Three common diseases (diabetes mellitus, chronic lung disease, and other cancer) that predicted competing mortality in younger men were not predictors of competing mortality in men selected for radical prostatectomy aged 70 yr or older (hazard ratio [HR]:<1). Besides age (HR/yr: 1.08, p=0.0255), peripheral vascular disease (HR: 2.33, p=0.0195), cerebrovascular disease (HR: 2.23, p=0.0242), American Society of Anesthesiologists physical status class 3 (HR: 2.19, p<0.0001), current smoking (HR: 2.18, p=0.0098), and lower or unknown level of education (HR: 2.07, p=0.0002) were independent predictors of competing mortality in patients aged 70 yr or older. Combining these five conditions in a score might provide a superior comorbidity measure in this particular population.

PATIENT SUMMARY

Stricter selection may diminish the prognostic significance of several common diseases in men selected for radical prostatectomy aged 70 yr or older whereas other parameters (peripheral vascular disease, cerebrovascular disease, American Society of Anesthesiologists physical status class 3, current smoking, and level of education) sustained their meaningfulness and should be taken into consideration when the risk of competing mortality is estimated.