Hypothesis / aims of study
Nocturia is the most common lower urinary tract symptom (LUTS) in both sexes, with increasing prevalence with advancing age , yet it is also one of the most under-reported. This might be explained by healthcare providers (HCP) not initiating the conversation regarding urinary symptoms or that patients experience embarrassment or perceive the symptom to be a consequence of aging . As a supplement to anamnesis, there exist several tools that help HCPs gauge the severity of nocturia and quantify the symptom: The Lower Urinary Tract Symptom Score Questionnaire (LUTSS)  and bladder diaries. While they may be useful standalone measures of nocturia, the degree to which these modalities correlate with each other might shed light on the clinical significance and benefit of incorporating multiple instruments, as opposed to the alternative of employing a single instrument, in the evaluation of nocturia. Thus, the purpose of this study is to evaluate the correlation between the number of reported nocturic episodes in anamnesis, 24-hour electronic bladder diaries (24HBD) based on a mobile app*, and metrics from the LUTSS.
Study design, materials and methods
A database from a mobile app* was queried to identify patients ≥18 years old and who reported nocturia, defined as at least one episode of waking up to urinate at night during sleep hours, on their 24HBD, LUTSS, and/or on chart review (anamnesis) from 2015 through 2018. Data from bladder diaries, LUTSS, and chart review were contemporaneously matched within a two-week period, provided that there was no change in symptoms or treatment. The patients were then subsequently de-identified after matching. For individuals with multiple bladder diaries and questionnaires, each contemporaneous set was analyzed as separate, unrelated entries. Additional data recorded include age, sex, and primary and secondary clinical diagnoses. Pearson’s correlation coefficient was used to assess the correlation between number of nocturic episodes reported in the following sets of variables: a) 24HBD and LUTSS, b) 24HBD and anamnesis, and c) LUTSS and anamnesis.
The number of nocturic episodes reported on 277 24HBD, 277 LUTSS, and 186 anamnesis accounts from 106 unique medical records (each medical record documented multiple patient encounters, with each encounter defined as an individual, separate anamnesis), collected from 66 men and 40 women (mean age 58 years, SD 16) were matched contemporaneously within 2 weeks of each other to produce sets of entries comprised of up to 3 values each, yielding a total of 277 sets of entries. A total of 94 24HBD, 157 LUTSS, and 129 anamnesis accounts were excluded either due to lack of reported nocturic episodes or lack of quantitative values defining at least one nocturic episode on chart review. One hundred eighty-three 24HBD, 120 LUTSS, and 57 anamnesis each had ≥1 reported episodes of nocturia. The number of sets of entries with ≥1 contemporaneous nocturia episodes are listed as follows: 29 between all three instruments (24HBD, LUTSS, and anamnesis), 90 between 24HBD and LUTSS, 43 between 24HBD and anamnesis, and 33 between LUTSS and anamnesis. Additional data from chart review includes the patients’ primary and secondary clinical diagnoses, presented in Table 1. The following Pearson’s correlation coefficient (r) and p-values are presented as follows: 24HBD and LUTSS, r = 0.2870, p< 0.00001; 24HBD and anamnesis, r= 0.260, p<0.000012; LUTSS and anamnesis, r = 0.725, p<0.00001.
Interpretation of results
In this study, overall, there was only a weak correlation between the number of nocturic episodes reported on the 24HBD, LUTSS, and anamnesis. Such a weak correlation has been reported many times in other studies using different instruments and highlights 1) the variability of patient reported outcomes across different modes of symptom assessment and 2) the “checks and balances” role that each individual instrument has in relation to the others. It also brings into question the best approach towards incorporating different surveys in the evaluation of LUTS and the methods of understanding discrepancies between patient reported outcomes. However, the arbitrariness of the contemporaneous “matching” period used for the number of nocturic voids, which we defined as 2 weeks for this study, is definitely a factor in determining the congruency of outcomes of the different instruments and, by extension, the Pearson’s correlation coefficients. For example, the fact that only 29 sets of entries had reported nocturic episodes on all three instruments (24HBD, LUTSS, and anamnesis) illustrates the limitation of the (arbitrarily chosen) contemporaneous 2 week “matching” period. Interestingly, the correlation between LUTSS and anamnesis, based on this study, seems to be modest (r=0.725, p<0.00001). This result could illustrate the fact that the LUTSS provides a catalogue of the patients' symptoms over a longer period of time, such that any given contemporaneously matched anamnesis will likely parallel the responses on the LUTSS questionnaire. In contrast, the 24HBD represents a more rigid "snapshot" of the patients' symptoms from day to day, which inherently can have a lot of variability, and the low correlation between 24HBD and LUTSS could reflect this variability. Future studies done to determine the correlation between other qualitative and quantitative instruments for the evaluation of LUTS could be insightful if they can unveil a combination of instruments, when employed contemporaneously and in varying lengths of “matching” periods, that accurately measures symptoms experienced by the patient.
We utilized a 24HBD in this research, because, considering the poor compliance documented with longer diaries, we were willing to accept a lower test-retest reliability in return for a higher compliance rate . From a clinical standpoint, there are several options for obtaining a more accurate assessment of the number of nocturic episodes. One can simply have the patient complete a longer bladder diary, but even that, over a relatively short time span offers, at best, a "snapshot". Another method, which is what we routinely employ, is to confront the patient with the disparity between the instruments and ask him/her to try to reconcile the data based on his/her experience. The final method, which has not yet been fully exploited, is to have the patient use an at-home flowmeter for every night-time micturition over a long period of time.