Nocturia Quality-of-Life questionnaire is a useful tool to predict nocturia and a risk of falling in Japanese outpatients: A cross-sectional survey

Authors


Abstract

Objectives

To evaluate the Japanese version of the Nocturia Quality-of-Life questionnaire for prediction of night-time voiding and risk of falling.

Methods

A survey was carried out from October 2008 to June 2009 in outpatients at 15 general hospitals and 80 general clinics in Tochigi, Japan, using the Nocturia Quality-of-Life questionnaire, overactive bladder symptom score and self-administered questionnaires on night-time symptoms (awakening, number of voids, incontinence and falling).

Results

The survey was completed by 2494 participants (1154 men, 1208 women; mean age 63.2 ± 15.1 years). Overactive bladder was diagnosed in 625 participants (25.1%) according to the Japanese overactive bladder guideline using overactive bladder symptom score. Awakening during sleep was reported by 80.1% of the participants, and 70.4% awakened to go to the toilet. The mean Nocturia Quality-of-Life score was 86.8 ± 16.9. The Nocturia Quality-of-Life score was lower in patients with overactive bladder, benign prostatic hyperplasia, diabetes, hypertension and cardiovascular diseases. The Nocturia Quality-of-Life score was significantly decreased in patients with night-time symptoms (P < 0.001). Nocturia Quality-of-Life scores and those for subdomains were correlated with overactive bladder symptom score. Nocturia Quality-of-Life ≤90 had 63.1% sensitivity and 78.6% specificity in indicating night-time voiding more than twice, and Nocturia Quality-of-Life questionnaire ≤80 had 70.2% sensitivity and 79.5% specificity in indicating the probability of falling at least once. Logistic analysis showed that 10-year increase in age and overactive bladder in all participants were significant risk factors for Nocturia Quality-of-Life ≤90.

Conclusions

The Nocturia Quality-of-Life questionnaire represents a useful tool to predict nocturia and risk of falling in Japanese patients.

Abbreviations & Acronyms
BPH

benign prostatic hyperplasia

CI

confidence interval

N-QOL

Nocturia Quality-of-Life questionnaire

OAB

overactive bladder

OAB-q

overactive bladder questionnaire

OABSS

overactive bladder symptom score

QOL

quality of life

ROC

receiver operating characteristic

Introduction

Demographic studies have shown that the frequency of nocturia increases with age,[1-3] and that increased night-time frequency of voiding leads to bone fracture, decreased QOL and increased risk of death in the elderly.[4, 5] These findings have caused considerable interest in this condition, but in clinical settings many elderly people accept nocturia as an aging symptom, and the degree to which it is viewed as an irritant varies from person to person. Thus, for the treatment of nocturia, an appropriate evaluation of the effect of nocturia on daily QOL is required, in addition to an understanding of the pathology and symptoms.

The Medical Outcomes Study Short Form-36 is a generic questionnaire that cannot detect the influence of nocturia on QOL, whereas the OAB-q is a disease-specific questionnaire that has been used to show that increased night-time frequency of voiding decreases QOL.[2] However, the OAB-q is not specifically based on nocturia. For this reason, N-QOL was prepared, and has now been translated into 16 languages and is used worldwide.[6, 7] The N-QOL includes two domains, Sleep/Energy and Bother/Concern, and the total score and the scores for each domain were calculated on a scale of 0–100, with 100 indicating the best condition. The Japanese version of the N-QOL,[8, 9] which was translated from the N-QOL,[6] has been validated. The OABSS developed by Homma et al. was used to evaluate OAB.[10, 11] The OABSS questionnaire can be used to grade daytime frequency, night-time frequency, urgency and urgency incontinence (see Appendix I). In the current study, nocturia-related QOL was investigated in the outpatients in Japan using the N-QOL. The objective of the present study was to investigate the relationships of N-QOL scores with night-time frequency more than twice, and fall or about to fall during night-time.

Methods

Self-administered questionnaires were carried out for outpatients who visited hospitals and clinics in Tochigi Prefecture from September 2008 to February 2009. The patients completed the N-QOL and OABSS, as well as questionnaires on age, sex and night-time symptoms, such as awakening during sleep, night-time incontinence and falling as a result of voiding at night. Patients also reported whether they had underlying diseases, such as BPH, hypertension, diabetes and cardiovascular diseases, in the questionnaire. OAB was defined according to the Japanese OAB guidelines; patients with an OABSS urgency score of 2 or higher, which indicates urgency of urination at least once each week, and a total OABSS score ≥3.

Unpaired t-test or the Jonckheere–Terpstra trend test were used to evaluate the relationships of N-QOL scores and patients' backgrounds. The correlations between total N-QOL scores and OABSS for each item of the questionnaire were evaluated by Spearman's rank correlation analysis. Relationships with a correlation coefficient of ≥0.4 were judged to be significant. A ROC curve was constructed to identify the predictive cut-off value of the N-QOL score, which indicated night-time voiding more than twice and being about to fall at least once a year. A multiple logistic regression analysis was used to identify independent risk factors for N-QOL less than the determined cut-off value according to sex. Variables included 10-year increase in age, OAB, BPH, hypertension diabetes and cardiovascular disease. P < 0.05 was considered to be significant in these analyses.

Results

The answers were obtained from 2494 patients (1154 males, 1208 females, and 132 unknown) in 15 general hospitals and 80 general clinics. The departments that consultations were made included internal medicine (1140 patients), urology (276 patients), gynecology and obstetrics (142 patients), orthopedics (100 patients), surgery (65 patients), and cardiovascular diseases (32 patients). The mean ± SD age of the patients was 63.2 ± 15.1 years (less than 40 years in 7.2% of patients, 40–49 years in 10.2%, 50–59 years in 17.8%, 60–69 years in 21.7%, over 70 years in 37.6% and unknown in 5.6%). OAB was noted in 25.1%.

Awakening at night was reported by 80.1%. The reasons for awakening at night were as follows: 1757 (70.4%) for urination, 247 (9.9%) for severe heat or cold, 231 (9.3%) for dry mouth, 176 (7.1%) for noise, 139 (5.6%) for anxiety and 129 (5.2%) for pain. The mean ± SD N-QOL score was 86.8 ± 16.9. The distribution of N-QOL scores is shown in Figure 1. Approximately 63% of the patients had a total N-QOL score >90. The relationship between patient background and the N-QOL score is summarized in Table 1. Univariate analysis showed that the N-QOL score in males was significantly lower than that in females. The N-QOL score was significantly lower in patients with underlying diseases, such as OAB, BPH, hypertension, diabetes and cardiovascular disease, compared with those who did not have these diseases (all P < 0.001). The N-QOL score was significantly lower in patients who complained of awakening during sleeping than in those who did not have this complaint. The N-QOL score significantly decreased in line with increases in the frequencies of night-time voiding, night-time incontinence and night-time falling (all P < 0.001). The total OABSS and the individual OABSS, the total N-QOL and N-QOL sub-domain scores, and the correlation between N-QOL scores and OABSS are summarized in Table 2.

Figure 1.

Distribution of N-QOL scores.

Table 1. Relationships between patient background factors and N-QOL scoresThumbnail image of
Table 2. Relationships (Spearman's correlation coefficients) between OABSS and N-QOL scores
OABSSN-QOL
Total (86.9 ± 16.7)Sleep/Energy (86.6 ± 17.6)Bother/Concern (87.2 ± 18.5)
  1. aA correlation coefficient ≥0.4 was taken as evidence of convergent validity. Numbers in parentheses are mean ± SD of OABSS and N-QOL scores.
Total (3.33 ± 3.08)−0.5966a−0.4898a−0.6060a
Daytime voiding score (0.55 ± 0.58)−0.2433−0.1922−0.2575
Night-time voiding score (1.37 ± 1.07)−0.5389a−0.4450a−0.5361a
Urgency score (0.98 ± 1.47)−0.4461a−0.3694−0.4616a
Urgency incontinence score (0.47 ± 1.09)−0.3514−0.2885−0.3707

To identify the predictive cut-off value of the N-QOL score, which indicated night-time voiding more than twice and being about to fall at least once a year, we constructed ROC curves of N-QOL score (Fig. 2). N-QOL score ≤90 had 63.1% sensitivity and 78.6% specificity in indicating night-time voiding more than twice, and N-QOL score ≤80 had 70.2% sensitivity and 79.5% specificity in indicating being about to fall at least once.

Figure 2.

ROC curves of N-QOL in (a) predicting nocturia (night-time voiding more than twice) and (b) being about to fall at least once. A N-QOL score ≤90 had 63.1% sensitivity and 78.6% specificity in indicating night-time voiding more than twice, and a N-QOL score ≤80 had 70.2% sensitivity and 89.5% specificity in indicating being about to fall at least once.

We next used multivariate logistic analyses to identify independent risk factors for N-QOL less than these cut-off values according to sex. Multivariate logistic analyses showed that older age and OAB in both sexes were significantly associated with N-QOL score of 90% or lower; odds ratios in males were −0.2 (95% CI −0.3 to −0.1) for 10-year increments of age and −11.6 (95% CI, −13.8 to −9.5) for OAB. Odds ratios in females are −0.1 (95% CI, −0.2 to −0.0) for 10-year increments of age and −17.4 (95% CI, −19.7 to −15.0) for OAB (Fig. 3).

Figure 3.

Logistic regression analysis of risk factors for a decreased N-QOL score (<90) in (a) males and (b) females. A 10-year increase in age, diabetes, cardiovascular diseases and OAB in both males and females, and prostate hyperplasia in males were investigated as potential factors that decreased the N-QOL score to <90.

Discussion

As shown in an epidemiological study by Homma et al., nocturia is the most commonly observed symptom and also the symptom that has the most influence on QOL among lower urinary tract symptoms in males and females.[1] Furthermore, the causes of nocturia are multifactorial; including storage dysfunction, such as OAB; nocturnal polyuria and sleep disturbance.[5] In recent years, relationships of nocturia with underlying lifestyle-related diseases (hypertension, diabetes mellitus, cardiac diseases, renal diseases, sleep apnea syndrome),[12, 13] falling due to voiding at night and even a shortened life[4, 14] have been reported. Thus, it is important to investigate the relationships between nocturia and underlying diseases in outpatients at various medical care departments.

The current study was thought to be the first to clarify the relationships between N-QOL scores and underlying diseases, OABSS, and frequency of falling. In addition, the present results provide the first validation of N-QOL in a cross-sectional survey in Japanese outpatients from various medical care departments. Patients who visited a department of urology accounted for at most 10% of the participants in this survey, and most of these patients actually visited a hospital with chief complaints of something other than urinary disturbance. Thus, it is particularly interesting that, despite these facts, 70% of the participants woke as a result of voiding at night (Table 1). The OABSS night-time voiding score and the N-QOL Sleep/Energy domain score showed the strongest correlation (Table 2). These results are consistent with the report by Schneider et al.,[14] in which it was shown that nocturia is the most influential symptom for daily life and sleep disturbance among urological diseases. It is also of note that urgency correlated with N-QOL, and specifically with the Bother/Concern subdomain. Tsujimura et al. also found that nocturia and urgency of urination are influential factors for quality of sleep in patients with obstructive sleep apnea syndrome.[12]

As urgency is an essential symptom of OAB, consideration of OAB is important in treating patients who complain of nocturia. Furthermore, our multivariate analysis identified a 10-year increase in age and overactive bladder as independent risk factors for a decrease of the N-QOL score in all participants (Fig. 3). In contrast, BPH did not appear to be a risk factor. An epidemiological study in American males reported that a 10-year increase in age, non-Hispanic black people, aggravated health condition by self-evaluation, major depression, hypertension and arthritis, but not BPH, were risk factors for causing voiding twice or more at night.[13] These findings are consistent with those in the current study, and this shows that the N-QOL score properly reflects night-time symptoms.

N-QOL is a new score that reflects nocturia-related QOL. N-QOL scores were significantly lower in patients with awakening during sleep compared with those without this condition (Table 1). Because night-time voiding twice or more at night can be highly bothersome and thus symptomatic,[1] we investigated which N-QOL score could be a cut-off value that relates to night-time voiding frequency more than twice. In our present study, N-QOL score <90 had 63.1% sensitivity and 78.6% specificity for estimating night-time voiding frequency more than twice. Thus, a N-QOL score <90 could be a possible criterion for determining nocturia.

In addition, there was a tendency for N-QOL scores to be lower depending on the increasing number of night-time incontinence and falling as a result of voiding at night (Table 1). The risk of night-time falling increases with night-time frequency. Stewart et al. found that voiding three times or more at night increased cases of bone fracture caused by falling by 2.15-fold.[15] Nakagawa et al. also found that voiding twice at night can be a risk for bone fracture.[4] The cut-off value of N-QOL score ≤80 could show the risk of being about to fall at least once in the present study (Fig. 2b). Thus, a N-QOL score ≤80 could be a criterion for selecting patients who might require additional care to prevent possible bone fracture caused by falling. Furthermore, N-QOL score ≤90 might indicate the risk of nocturia twice or more. It has been reported that night-time voiding twice or more at night can be highly bothersome and thus symptomatic.[16, 17] Therefore, N-QOL <90 might be influenced on the worsening of daily life.

One limitation of the present study was selection bias of the patients. In a survey of randomly selected patients identified from the national resident register, Homma et al. found a rate of night-time voiding of once or more of 69% and a frequency of OAB of 12.6%.[1] In the present study, the frequency of nocturia was similar to that in Homma et al., but the frequency of OAB was higher, at 25%. This discrepancy could have arisen because the current study did not include healthy persons without underlying disease. However, we chose this approach because the effect of nocturia on decreasing QOL is more frequently observed in patients with underlying diseases. The frequency of OAB is also likely to differ when the target medical care department for a survey differs, but as the objective of the present study was to investigate the usefulness of the N-QOL for evaluation of nocturia, this selection bias might be ignored. The present results also suggest that there are many nocturia patients and potential OAB patients in multiple clinical settings. These results could indicate that therapeutic intervention for nocturia and OAB is necessary not only in urology, but in many medical care departments including internal medicine.

The results of the present study showed that the frequency of falling as a result of voiding at night was likely to be higher in patients with night-time voiding. Recently, Hunter et al. pointed out that there was insufficient evidence to determine whether anticholinergic agents were useful to reduce the risk of bone fracture caused by nocturia as a result of OAB, and they also suggested the need to evaluate the risk of bone fracture caused by OAB.[18] We conclude that the N-QOL could be a useful tool for evaluating the influence of nocturia on daily life and for examining therapeutic effects on the risk of bone fracture as a result of nocturia. The present results suggest that a score on the N-QOL of ≤90 indicates a possible influence of nocturia twice or more, and that a score of ≤80 indicates a risk of falling.

Acknowledgments

We thank all the participants for their assistance with data collection.

Conflict of interest

None declared.

Appendix: Appendix I: Overactive Bladder Symptom Score (OABSS)

At what frequency have you experienced the following symptoms? Please circle the score that applies best to your condition in the past week.

QuestionSymptomsScoreFrequency
1How many times do you typically urinate from waking in the morning until sleeping at night?07 or less
18–14
215 or more
2How many times do you typically wake up to urinate from sleeping at night until waking in the morning?00
11
22
33 or more
3How often do you have a sudden compelling desire to urinate that is difficult to defer?0Not at all
1Less than once a week
2Once a week or more
3About once a day
42–4 times a day
55 times a day or more
4How often do you leak urine because you cannot defer the sudden desire to urinate?0Not at all
1Less than once a week
2Once a week or more
3About once a day
42–4 times a day
55 times a day or more
 Sum of scores  

If the question text and options are equivalent, the format does not necessarily have to be that shown above. In this table, the duration is defined as “the past week”, but depending on the usage it can be amended to, for example, “the past 3 days” or “the past month”. Whatever the case, it is necessary to specify the duration.

Patients with an OABSS urgency score of 2, which indicates urgency of urination at least once each week, and an OABSS score ≥3 are recommended for diagnosis with OAB.

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