Nocturia commonly occurs alongside other symptoms of bladder dysfunction at night, such as urinary urgency, urgency incontinence and enuresis (1). Quantification of nocturnal bladder dysfunction will enable evaluation of the impact of individualised treatment.  A symptom-specific score for bladder dysfunction at night has recently been developed to capture clinically relevant domains (2). The aim of this study was to test the nocturnal bladder symptom score (NITE-SS) and to generate a robust short form.

The NITE-SS measure was developed from a subjective patient-orientated perspective and refined following patient feedback (2).  In this study, factor analysis was performed on completed measures with the aim of reducing the number of variables.  Endorsement frequency was obtained for all items and sub-scales using counts; items with a high floor effect (i.e. >70% of responses ‘never’ or its equivalent) or >20% missing data were noted. Principal component analysis was used to extract the maximum variance explained by the first factors and then by subsequent factors. We report factor loading, eigenvalues and factor scores from a sample of 151 NITE-SS completed by individuals older than 70 years who were either inpatients at our hospital or attending outpatient clinics. Analyses justified items retained in the final NITE-SS. The institutional ethics committee (QA2021045) approved the study.

Of the 151 NITE-SS data sets, 98 were completed by inpatients and 53 by community-dwelling older adults attending a hospital continence clinic.  Females comprised 68% of the responders. The data set contained no missing values. Nocturia of at least twice per night, frequent urinary urgency, incontinence while asleep and incontinence en route to the bathroom at night were reported by 70.8%, 47%, 20.6% and 19.8% of participants respectively. 

Five items showed a floor effect.  All correlation coefficients were <0.8 indicating no multi-collinearity. Kaiser-Meyer-Olkin = 0.83; Bartlett’s test of sphericity was significant. Four factors returned an eigenvalue >1.0 explaining a cumulative variance of 59%. Specific items related to symptom description were retained. The decision tree for removing redundant items considered weighting in multiple components, inter-relationship, likelihood of change post-intervention and low endorsement frequency.

Three factors were identified in the measurement of bladder symptoms at night: sleep, incontinence and personal bother attributable to nocturnal LUTS. The final metric (Figure 1) contained 13 items each scored as 0 for lowest level of attribute through to 4 for most negative.

The new metric, NITE-SS, has undergone principal component analysis and been reduced to 13 items.  Reliability and sensitivity are currently being established.

Nguyen HX, Penukonda S, Stephen S, et al. Wake-up call: 4 out of 5 older hospitalised patients have nocturnal lower urinary tract symptoms. Australasian Journal on Ageing. 2021; 40(4): 457-460
Bower WF, Ervin CF, Whishaw DM, et al. Initial development of a patient-centred symptom score for bladder dysfunction at night in older hospitalised patients. Australian and New Zealand Continence Journal 2021; 27(3):71-76

Continence 2S2 (2022) 100333
DOI: 10.1016/j.cont.2022.100333