Nocturia is a common complaint with a huge impact on quality of life that causes urologic consultation. At present, frequency volume chart (FVC) is an optimal tool for the evaluation of nocturia [1,2], but it is related to patient compliance and burden. The International Prostate Symptom Score (IPSS) is a widely used questionnaire in the outpatient evaluation and quantification of lower urinary tract symptoms (LUTS). Aim of the study was to evaluate the prevalence of nocturia in men complaining LUTS and the role of IPSS in men with nocturia.

An observational, prospective study was performed involving two Urological Departments. 461 consecutive male patients with LUTS were recruited from September 2016 to November 2017. The following data were recorded: demographic characteristics, urological history, and self-administered IPSS. They were requested to complete a 3-days FVC, indicating “bedtime” and “waking time”. The mean number of nightly voids was correlated to IPSS domains, in particular to: i) IPSS nocturia score (domain 7), ii) total IPSS score (domains 1-7), iii) IPSS quality of life score (domain 8). Statistical analysis was performed using T student and Mann-Whitney test and Bravais-Pearson correlation test.

162/461 patients (35%) completed both IPSS and 3-days FVC (mean age 70,95 ± 8.04 years). Prevalence of reported nocturia was 86,42%, with a mean number of nocturnal voiding of 1.36 ± 0,98 per night. Figure 1 shows distribution of mean episodes of nocturnal voiding per night. Figure 2 documents the difference in mean episodes of nocturia between IPSS and 3-days FVC (absolute values). The differences in episodes of nocturnal voiding between IPSS and 3-days FVC according to patients age are reported in Table 1. Table 2 shows the comparison of median IPSS domains 7, 8 and IPSS total score according to average number of nocturia episodes on the 3-days FVC. Considering a threshold of 70 years of age, no significant difference was found in episodes of nocturnal voiding between IPSS and mean number of nocturnal voiding at 3-days FVC according to patients age (Table 3). Median IPSS domain 7 and total IPSS score were higher when the mean number of night voids was > 1 (p<0.001). IPSS domain 8 did not reach any statistical difference (p>0.05). Bravais-Pearson correlation test showed a moderate positive correlation (+0,42) between the mean number of nightly voids on the 3-days FVC and IPSS 7.

This study showed a high prevalence of nocturia (86,4%) among patients complaining LUTS (according with other literature results). Most patients (62,34%) reported a discrepancy between IPSS nocturia score and mean nightly voids in the 3-days FVC, in particular in younger patients. The difference was high (>2) in an important part of the cohort (28%). Therefore IPSS nocturia score seems poorly reliable in the assessment of nocturia. According with previous data, overestimation of the nocturia episodes in the IPSS was more common than underestimation [3]. Poor correlation between IPSS domain of quality of life and nightly voids may suggest that also other factors are correlated to the patients bother and severity of urinary symptoms. Age did not affect the difference between IPSS and mean number of nocturnal voiding.

Due to his high prevalence, nocturia is one of the most complained among LUTS. The 3-days FVC remains the most important and reliable tool for the evaluation of males with LUTS and nocturia. IPSS is an easy and quick questionnaire, but its utility in the specific assessment of nocturia remains uncertain and, according to our data, almost inaccurate.

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