Nocturia common in Japanese patients

Dec 2 2013

Results from an outpatient-based study indicate that nocturia is common among Japanese patients, with men, the elderly, and those with hypertension at the greatest risk.

Researchers Minoru Miyazato (University of the Ryukyus, Okinawa, Japan) and colleagues say that the majority of previous studies into nocturia prevalence have come from referral-based samples and therefore had limited generalizability to the overall population.

But their findings, which included patients regularly attending a general medical clinic, point to a prevalence of nocturia of around a third in adults with concomitant medical problems.

The team studied 347 patients who attended a general medical clinic at least twice in a 6-month period. All patients had a history of Type 2 diabetes, hypertension, hyperlipidemia, cerebrovascular disease, ischemic heart disease, or depression. The overall study population had a mean age of 58.6 years, 53.8% were male, and 23.7% had previously visited a urologic clinic.

Overall, 120 (33.8%) patients had clinically significant nocturia, defined as typically voiding two or more times per night within the previous month.

In multivariate analysis, being aged 70 years or over versus 50–70 years was significantly associated with a higher rate of nocturia, at 57.7% versus 28.3%. Additionally, being male (38.9 vs 26.7% in women) or having hypertension (37.6 vs 22.4% in those without) was independently associated with the condition. There also seemed to be an association between depression and the condition, but this was of borderline significance.

While the prevalence of nocturia in this population was higher than previously reported, Miyazato say that the risk factors associated with the condition are unsurprising.

“[A]ging is the most definitive risk factor for nocturia,” they write. “Because it has been reported that nocturnal bladder capacity decrease[s] with age, [it] may be the primary cause of nocturia.”

Additionally, they say the greater prevalence of the condition among men is likely due to benign prostatic hyperplasia, which also becomes more common with age. And, hypertension has previously been linked to nocturia in patients with sleep apnea and chronic kidney disease.

The authors conclude that, given the high prevalence of nocturia in this population with existing medical problems, “it is important to evaluate not only urological problems but other medical problems in patients with nocturia.”

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