Do LUTS Predict Mortality? An Analysis Using Random Forest Algorithms

Abstract

Purpose

To evaluate a random forest (RF) algorithm of lower urinary tract symptoms (LUTS) as a predictor of all-cause mortality in a population-based cohort.

Materials and Methods

A population-based cohort of 3143 men born in 1924, 1934, and 1944 was evaluated using a mailed questionnaire including the Danish Prostatic Symptom Score (DAN-PSS-1) to assess LUTS as well as questions on medical conditions and behavioral and sociodemographic factors. Surveys were repeated in 1994, 1999, 2004, 2009 and 2015. The cohort was followed-up for vital status until the end of 2018. RF uses an ensemble of classification trees for prediction with a good flexibility and without overfitting. RF algorithms were developed to predict the five-year mortality using LUTS, demographic, medical, and behavioral factors alone and in combinations.

Results

A total of 2663 men were included in the study, of whom 917 (34%) died during follow-up (median follow-up time 15.0 years). The LUTS-based RF algorithm showed an area under the curve (AUC) 0.60 (95% CI 0.52–0.69) for five-year mortality. An expanded RF algorithm, including LUTS, medical history, and behavioral and sociodemographic factors, yielded an AUC 0.73 (0.65–0.81), while an algorithm excluding LUTS yielded an AUC 0.71 (0.62–0.78).

Conclusion

An exploratory RF algorithm using LUTS can predict all-cause mortality with acceptable discrimination at the group level. In clinical practice, it is unlikely that LUTS will improve the accuracy to predict death if the patient’s background is well known.

Keywords:

• lower urinary tract symptoms
• mortality
• machine learning
• cohort studies

Abbreviations

LUTS, Lower urinary tract symptoms; RF, random forest; ML, machine learning; TAMUS, Tampere Ageing Male Urologic Study; DAN-PSS-1, Danish Prostatic Symptom Score; BMI, body mass index; AUC, area under the curve.

Disclosure

Jori S Pesonen has received a lecture honorarium from Astellas, Boston Scientific, and Ferring and attended a scientific congress as a guest for Orion. Teuvo Tammela has worked as a consultant for Astellas, Pfizer and Bayer AG. The other authors have no relevant financial or non-financial interests to disclose for this work.

Additional information

Funding

The TAMUS study was financially supported by the Päivikki and Sakari Sohlberg Foundation and the Competitive State Research Financing of the Expert Responsibility area of Tampere University Hospital (9V065 and 9×055). State Research Funding (Finland) was used for data collection. The work of Jonne Åkerla was funded by the Finnish Urological Association. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.