Symptom-based Clustering in Men with Lower Urinary Tract Symptoms

New research has employed an algorithm to identify novel subgroups of men with different lower urinary tract symptoms (LUTS) based on detailed symptom information—results that could help in understanding and treating LUTS in the future. LUTS are highly prevalent in both males and females, but many people who seek help from healthcare providers for LUTS experience neither total nor permanent resolution of their symptoms with current management approaches. One of the barriers to improving diagnosis and management of LUTS is incomplete knowledge and imprecise classification of subtypes of LUTS and their associated causes. There are a wide variety of LUTS that people can experience, such as problems with emptying (voiding) urine from the bladder, which may be caused by problems in the urinary tract or may originate elsewhere in the body. Even people with similar symptoms may have different underlying urinary tract conditions.

A study conducted through the NIDDK-supported Symptoms of Lower Urinary Tract Dysfunction Research Network (LURN) sought to overcome some of the barriers to diagnosis and management. Using a consensus clustering algorithm—a novel approach that did not rely on conventional clinical definitions to group patients—they analyzed responses to self-administered questionnaires to identify distinct symptom signatures in 503 care-seeking men with LUTS, the majority of whom were Caucasian with an approximate average age of 61. Four separate symptom clusters (CL1-4) were identified among participants, with the following characteristics. The 166 participants in CL-1 had predominant urinary symptoms of hesitancy (difficulty starting or maintaining urine stream), straining, weak stream, incomplete bladder emptying, frequency, and nocturia (waking from sleep to urinate)—a pattern suggestive of bladder outlet obstruction. The 93 participants in CL-2 mainly had symptoms of post-void dribbling and post-void urinary incontinence. The 114 participants in CL-3 had predominant symptoms of urinary frequency and nocturia without incontinence. The 130 participants in CL-4 had symptoms of severe urinary frequency, urgency, and urgency incontinence.

Future research may examine these four symptom clusters in the context of biomarkers, and how the brain and/or nervous system may be influencing bladder function. For example, neuroimaging may identify differences in brain structure and function as it relates to bladder control, and sensory testing could explore whether differences exist in nervous system responses to auditory (hearing) and pain stimuli. Findings from such studies could provide insight into the complexities of male LUTS, while validation studies can help to determine if the groupings are helpful to clinical diagnosis and management of LUTS across men in the U.S. population. Furthermore, the phenotypic clusters identified by the LURN consortium provide a foundation in which to test the effectiveness of treatments.