Lower urinary tract symptoms (LUTS) are among the most common complaints encountered in urological and general medical practice among aging men, with prevalence increasing steadily after the fifth decade of life.[1] LUTS are broadly classified into storage symptoms (frequency, urgency, nocturia), voiding symptoms (hesitancy, weak stream, straining, intermittency, terminal dribbling), and post-micturition symptoms (sensation of incomplete emptying, post-micturition dribble).[2] Benign prostatic hyperplasia (BPH) remains the single most common underlying cause of LUTS in aging men, although detrusor dysfunction, urethral stricture, bladder neck obstruction, and neurogenic causes may also contribute to the symptom complex.[3] Population-based studies from India have shown that nearly one in every two men above the age of 50 years experiences some degree of LUTS, with a substantial proportion remaining undiagnosed and untreated due to poor health-seeking behaviour and lack of awareness.[4] Patwardhan et al. reported a high prevalence of moderate to severe LUTS among men attending outpatient clinics in western India, emphasizing the need for objective screening tools in routine practice.[5] The International Prostate Symptom Score (IPSS), a self-administered questionnaire validated by the American Urological Association, remains the most widely used tool for grading the severity of LUTS.[6] It classifies symptoms as mild (score 0-7), moderate (score 8-19), or severe (score 20-35). However, IPSS is inherently a subjective instrument, dependent on patient perception, education level, cultural background, and recall, and therefore may not always correlate precisely with the actual degree of bladder outlet obstruction or voiding dysfunction.[7] Uroflowmetry is a simple, inexpensive, non-invasive urodynamic investigation that objectively records the rate of urine flow during voiding, providing parameters such as maximum flow rate (Qmax), average flow rate (Qavg), voided volume, flow time, and time to maximum flow.[8] It is widely recommended as an initial screening investigation in the evaluation of men with LUTS, as it helps differentiate between obstructive and non-obstructive patterns of voiding dysfunction and can guide further invasive testing such as pressure-flow studies.[9] Sarma and Wei described uroflowmetry as a cost-effective triage tool, particularly valuable in outpatient settings with high patient volumes.[10] Several international studies have attempted to correlate uroflowmetry parameters with IPSS severity, with variable results, as symptom severity is influenced not only by bladder outlet obstruction but also by detrusor overactivity, bladder sensation, and psychological factors.[11] In the Indian context, uroflowmetry is particularly relevant given resource constraints that often limit access to more sophisticated pressure-flow urodynamic studies, making it imperative to establish how well this simple test correlates with patient-reported symptom severity.[12] Gupta et al., in a study conducted in northern India, reported a significant inverse correlation between Qmax and IPSS score, supporting the use of uroflowmetry as a screening adjunct in Indian men with LUTS.[13] Despite the widespread use of both IPSS and uroflowmetry in clinical practice, there remains a paucity of prospective Indian data specifically correlating individual uroflowmetry parameters with graded severity of LUTS across mild, moderate, and severe categories. This study was therefore undertaken with the aim of prospectively evaluating the correlation between uroflowmetry parameters and IPSS-graded severity of LUTS in adult male patients attending a tertiary care centre. Aims and Objectives To assess the correlation between uroflowmetry parameters (maximum flow rate [Qmax], average flow rate [Qavg], voided volume, flow time, and post-void residual urine [PVR]) and the severity of LUTS as measured by IPSS in adult male patients.

Study Design and Setting This was a hospital-based, prospective, observational, cross-sectional analytical study conducted in the Department of Urology of a tertiary care teaching hospital over a period of 18 months, after obtaining approval from the Institutional Ethics Committee. Written informed consent was obtained from all participants prior to enrolment, in accordance with the Declaration of Helsinki. Sample Size Based on a previous study reporting a correlation coefficient (r) of approximately 0.45 between Qmax and IPSS score, and using a two-sided significance level (α) of 0.05 with 90% power, a minimum sample size of 138 was calculated. Accounting for a 10% non-response/dropout rate, a total of 150 patients were enrolled in the study. Inclusion Criteria 1. Adult male patients aged 40 years and above presenting with LUTS. 2. Patients willing to give written informed consent and able to comply with study procedures. 3. Patients able to void a minimum of 150 mL during uroflowmetry. Exclusion Criteria 1. Patients with a prior history of lower urinary tract or prostate surgery. 2. Patients with confirmed urethral stricture disease. 3. Patients with acute urinary retention or indwelling catheter at presentation. 4. Patients with neurogenic bladder dysfunction or known neurological disease affecting micturition. 5. Patients with active urinary tract infection at the time of evaluation. 6. Patients with clinical or biochemical suspicion of prostate malignancy (PSA > 10 ng/mL or abnormal digital rectal examination). 7. Patients on medications known to affect bladder or urethral function (anticholinergics, alpha-blockers already initiated, etc.), unless washed out for a minimum of two weeks. Study Procedure All enrolled patients underwent a detailed clinical history, including duration and nature of LUTS, comorbidities, and drug history, followed by a focused general and local examination, including digital rectal examination. Symptom severity was assessed using the validated IPSS questionnaire, translated into the local vernacular language where required, and patients were categorized as follows: mild LUTS (IPSS 0-7), moderate LUTS (IPSS 8-19), and severe LUTS (IPSS 20-35). Free-flow uroflowmetry was performed using a calibrated electronic uroflowmeter in a private, comfortable setting, with patients instructed to void when they experienced a normal, natural urge, with a pre-void bladder volume between 150-450 mL as confirmed by ultrasonography. The following parameters were recorded for each patient: maximum flow rate (Qmax, mL/s), average flow rate (Qavg, mL/s), voided volume (mL), flow time (seconds), and time to maximum flow (seconds). Post-void residual urine (PVR) was measured by transabdominal ultrasonography within five minutes of voiding. Each patient performed the test twice, and the reading with the higher voided volume was taken as representative, in accordance with International Continence Society (ICS) good urodynamic practice guidelines.[14] Statistical Analysis Data were entered in Microsoft Excel and analysed using SPSS software (version 26.0). Continuous variables were expressed as mean ± standard deviation (SD) and categorical variables as frequencies and percentages. Comparison of uroflowmetry parameters across the three IPSS severity groups was performed using one-way analysis of variance (ANOVA) with post-hoc Tukey testing. Correlation between IPSS score and uroflowmetry parameters was assessed using Pearson's correlation coefficient (r) for normally distributed data. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal Qmax cut-off for predicting moderate-to-severe LUTS. A p-value of less than 0.05 was considered statistically significant.

A total of 150 adult male patients with LUTS were enrolled and completed the study protocol. The mean age of the study population was 61.4 ± 9.8 years (range 42-84 years). The demographic and baseline clinical characteristics of the study population are summarized in Table 1. Table 1: Demographic and Baseline Characteristics of Study Population (n = 150) Parameter Value Mean age (years) 61.4 ± 9.8 Age group 40-50 years, n (%) 24 (16.0%) Age group 51-60 years, n (%) 46 (30.7%) Age group 61-70 years, n (%) 51 (34.0%) Age group >70 years, n (%) 29 (19.3%) Mean BMI (kg/m²) 24.6 ± 3.1 Diabetes mellitus, n (%) 38 (25.3%) Hypertension, n (%) 52 (34.7%) Mean duration of symptoms (months) 14.8 ± 8.6 Mean prostate volume (mL, on USG) 38.7 ± 14.2 Mean serum PSA (ng/mL) 2.1 ± 1.4 On the basis of IPSS scoring, patients were categorized into mild, moderate, and severe LUTS groups. The distribution of patients according to symptom severity is shown in Table 2. Table 2: Distribution of Patients According to IPSS Severity Grade IPSS Severity Grade IPSS Score Range Number of Patients (n) Percentage (%) Mild 0-7 34 22.7 Moderate 8-19 70 46.7 Severe 20-35 46 30.6 Total 0-35 150 100.0 Mean uroflowmetry parameters were calculated for each IPSS severity group. A progressive and statistically significant decline in Qmax and Qavg was observed with increasing symptom severity, while post-void residual urine showed a corresponding progressive increase, as detailed in Table 3. Table 3: Comparison of Uroflowmetry Parameters Across IPSS Severity Groups (Mean ± SD) Parameter Mild (n=34) Moderate (n=70) Severe (n=46) p-value (ANOVA) Qmax (mL/s) 18.6 ± 3.2 13.4 ± 2.9 8.1 ± 2.4 <0.001 Qavg (mL/s) 10.2 ± 2.1 7.6 ± 1.8 4.9 ± 1.5 <0.001 Voided volume (mL) 268.4 ± 62.1 251.7 ± 58.4 232.6 ± 54.8 0.041 Flow time (seconds) 24.8 ± 5.6 31.2 ± 6.4 38.7 ± 7.9 <0.001 Time to max flow (seconds) 7.9 ± 2.1 10.6 ± 2.8 14.3 ± 3.4 <0.001 Post-void residual urine (mL) 18.4 ± 9.6 42.7 ± 16.3 78.5 ± 24.1 <0.001 Pearson's correlation analysis demonstrated a strong negative correlation between IPSS score and both Qmax and Qavg, and a moderate positive correlation between IPSS score and post-void residual urine. Voided volume and flow time showed weaker correlations with IPSS score. The correlation coefficients are presented in Table 4. Table 4: Correlation of IPSS Score with Uroflowmetry Parameters Uroflowmetry Parameter Pearson's Correlation Coefficient (r) p-value Strength/Direction Qmax -0.71 <0.001 Strong negative Qavg -0.64 <0.001 Strong negative Post-void residual urine +0.58 <0.001 Moderate positive Voided volume -0.22 0.006 Weak negative Flow time +0.47 <0.001 Moderate positive Prostate volume (USG) +0.39 <0.001 Weak-moderate positive On ROC curve analysis, a Qmax cut-off of ≤12 mL/s predicted moderate-to-severe LUTS (IPSS ≥8) with a sensitivity of 81.2% and specificity of 76.5% (area under curve = 0.86, p < 0.001), as summarized in Table 5. These findings support the clinical utility of Qmax as an objective screening parameter that closely parallels patient-reported symptom severity. Table 5: Diagnostic Performance of Qmax Cut-off (≤12 mL/s) for Predicting Moderate-to-Severe LUTS Parameter Value Sensitivity 81.2% Specificity 76.5% Positive predictive value 88.4% Negative predictive value 64.7% Area under ROC curve (AUC) 0.86 95% Confidence Interval 0.79 - 0.92 Additionally, flow pattern morphology was assessed qualitatively. A bell-shaped (normal) flow curve was seen in 28 (18.7%) patients, a plateau pattern suggestive of obstruction in 79 (52.6%) patients, and an intermittent/staccato pattern in 43 (28.7%) patients, the latter two being significantly more frequent in the moderate and severe LUTS groups (p < 0.001), as shown in Table 6. Table 6: Uroflowmetry Curve Pattern Distribution Across Severity Groups Flow Curve Pattern Mild (n=34) Moderate (n=70) Severe (n=46) Total (n=150) Bell-shaped (normal) 22 (64.7%) 6 (8.6%) 0 (0.0%) 28 (18.7%) Plateau (obstructive) 9 (26.5%) 48 (68.6%) 22 (47.8%) 79 (52.6%) Intermittent/Staccato 3 (8.8%) 16 (22.8%) 24 (52.2%) 43 (28.7%) Overall, the results of this study demonstrate a strong, statistically significant correlation between objective uroflowmetry parameters, particularly Qmax and Qavg, and subjectively assessed severity of LUTS as graded by IPSS, with a progressive worsening of flow parameters and increase in post-void residual urine across mild, moderate, and severe symptom categories.

This prospective study of 150 adult male patients with LUTS demonstrated a strong inverse correlation between IPSS score and both Qmax (r = -0.71) and Qavg (r = -0.64), along with a significant positive correlation between IPSS score and post-void residual urine (r = +0.58). These findings confirm that uroflowmetry, despite being a simple and inexpensive investigation, provides an objective physiological correlate of patient-reported symptom severity in men with LUTS.[15] The mean Qmax observed in our severe LUTS group (8.1 ± 2.4 mL/s) was consistent with values reported by Reynard et al. in a landmark uroflowmetry nomogram study, wherein a Qmax below 10 mL/s was associated with a high likelihood of bladder outlet obstruction.[16] Similarly, Jensen et al. demonstrated that Qmax declines progressively with increasing severity of voiding symptoms, corroborating the trend observed in our cohort.[17] Indian data on this subject remain relatively limited but broadly support our findings. Singh et al., in a study conducted at a tertiary care centre in northern India, reported a significant negative correlation between Qmax and IPSS (r = -0.68), closely mirroring the correlation coefficient observed in the present study.[18] Similarly, Deshmukh and colleagues, in a prospective study from Maharashtra, observed that patients with severe LUTS had a significantly lower mean Qmax (9.2 mL/s) compared to those with mild symptoms (19.4 mL/s), consistent with the trend seen in our results.[19] Rathi et al., in a South Indian cohort, further demonstrated that a Qmax cut-off of 12-13 mL/s offered good discriminatory value for identifying men with moderate-to-severe symptoms, a finding almost identical to the cut-off of 12 mL/s derived in our ROC analysis.[20] The positive correlation between post-void residual urine and IPSS severity observed in our study is also in agreement with prior Indian study. Kumar and Sharma reported that elevated PVR was significantly associated with higher IPSS scores and lower Qmax values among men attending a tertiary urology clinic in Delhi, supporting the practice of combining PVR estimation with uroflowmetry for a more complete objective assessment of voiding dysfunction.[21] This combination is particularly relevant in the Indian setting, where access to pressure-flow urodynamic studies is often limited by cost and infrastructure, making uroflowmetry with PVR estimation a practical and reproducible screening strategy.[22] The proportion of obstructive (plateau) and intermittent (staccato) flow patterns increasing with symptom severity in our study is consistent with the pathophysiological understanding that progressive bladder outlet obstruction from BPH leads to compensatory detrusor changes, initially resulting in a plateaued flow curve and, with further progression, in detrusor decompensation manifesting as an intermittent or staccato pattern.[23] Similar flow-pattern distributions were reported by Golomb et al. in a Western cohort, lending further support to the reproducibility of this observation across populations.[24] It is important, however, to acknowledge that the correlation between uroflowmetry parameters and IPSS, although statistically strong in this study, is not absolute. IPSS is a composite score incorporating storage as well as voiding symptoms, and factors such as detrusor overactivity, nocturnal polyuria, and psychological perception of symptom bother can influence the total IPSS independent of the degree of bladder outlet obstruction.[25] This may partly explain the moderate, rather than very strong, correlation seen with some individual parameters such as voided volume. Abrams emphasized that uroflowmetry alone cannot definitively distinguish bladder outlet obstruction from detrusor underactivity, and that pressure-flow studies remain the gold standard where diagnostic uncertainty persists, particularly prior to invasive intervention.[26] Nonetheless, given its non-invasive nature, low cost, and ease of repeatability, uroflowmetry remains an extremely valuable first-line objective test in the triage and follow-up of men with LUTS, particularly in high-volume outpatient settings typical of Indian tertiary care hospitals.[27] Verma et al. further advocated for the routine incorporation of uroflowmetry alongside IPSS in Indian primary and secondary care settings, given its potential to improve diagnostic accuracy without significantly increasing cost or invasiveness of the initial work-up.[28] Limitations This study has certain limitations. First, being a single-centre, hospital-based study, the findings may not be entirely generalizable to the community-dwelling population. Second, invasive pressure-flow urodynamic studies were not performed, and hence a definitive diagnosis of bladder outlet obstruction could not be established in all cases. Third, single-session uroflowmetry, although performed twice per protocol, is subject to intra-individual variability, and multiple repeat measurements may have further improved reliability. Larger, multicentric studies with longer follow-up and pressure-flow correlation are recommended to validate these findings further.

This prospective study demonstrates a statistically significant correlation between uroflowmetry parameters and the severity of lower urinary tract symptoms in adult male patients. Maximum flow rate (Qmax) and average flow rate (Qavg) showed a strong negative correlation, while post-void residual urine showed a significant positive correlation, with IPSS-graded symptom severity. A Qmax cut-off of approximately 12 mL/s demonstrated good sensitivity and specificity in predicting moderate-to-severe LUTS. These findings reinforce the role of uroflowmetry as a simple, reproducible, and cost-effective objective adjunct to symptom-based questionnaires such as IPSS in the routine evaluation of men with LUTS, particularly in resource-constrained settings such as India, and support its wider incorporation into standard clinical practice for initial assessment and follow-up of these patients.

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