Study design, materials and methods
In this IRB approved study, an established database was queried between 2015 and 2018 to identify men ≥18 years of age with LUTS, who completed the LUTSS questionnaire and a contemporaneous 24HBD. Men with significant changes in symptoms or management of symptoms in the two-week period were excluded from the analysis. The LUTSS questionnaire is a validated 14 item symptom questionnaire [2]. The OVS sub score is comprised of four questions relating to OVS: incomplete bladder emptying, intermittency, slow stream, and straining. The score ranges from 0-16, with 16 being maximum symptom severity. The 24HBD documents the time and volume of each void and whether it was accompanied by any OVS. The average number of voiding incidents over 24 hours accompanied by OVS was correlated with the OVS sub score using Pearson’s correlation coefficient (r).
Results
A total of 238 patients were included in the analysis (mean age 59, SD 16). A scatter-plot of the number of OVS micturition incidents versus the OVS sub score is shown (Figure 1). Three observations are noteworthy: 1) There is a significant, but weak positive correlation between the frequency of reported OVS incidents and the obstructive symptom score (r = .37, p< .001), 2) some patients recorded up to 18 OVS incidents but reported only mild symptoms (OVS sub score < 6), and 3) some patients with no recorded obstructed voiding incidents report severe symptoms (OVS sub score > 12).
Interpretation of results
The relatively weak correlation between reported symptom scores and bladder diaries reveals that perceptions of symptom severity, as reflected in symptom surveys, often do not align with the results of more objective tools like bladder diaries. This could reflect 1) a disconnect between a patient’s perception of their condition and objective reality, 2) temporal variations in symptoms that are more accurately captured by a patient’s subjective recollections over an extended time period compared to a time-limited bladder diary, or 3) the difficulty patients experience transposing their personal experience into the metrics of a symptom score and bladder diary.
A weakness in this study is that only a single 24HBD was utilized; longer bladder diaries have been associated with lower patient compliance [1]. A lower test-retest reliability was accepted in return for a higher compliance rate, but this may have affected the ultimate results. Of course, longer bladder diaries may diminish the difference between the results. Another option, which is what we routinely employed, is to confront the patient with the disparity between the instruments and ask him/her to try to reconcile the data.
Other published studies have demonstrated a higher correlation among a questionnaire and bladder diary. This is partially due to varying questionnaire and bladder diaries. Moreover, some of the studies were part of a larger drug trial study, explaining the difference in the correlation coefficient [3]. In these studies, a correlation was derived using the average number of obstructed voids as opposed to each individual patient’s obstructed voids.
Concluding message
This study demonstrates an unexpected disparity between one aspect of the 24HBD - obstructive voiding symptoms and a validated symptom questionnaire sub score that asks about OVS. This disparity is evident as a weak correlation coefficient (r = .37) between the 24HBD and LUTSS OVS sub score.
It appears that patients’ perceptions of symptom severity, as reflected in symptom surveys, often do not align with the results of more objective instruments such as bladder diaries. What is unequivocal, is that the two instruments are not redundant, but rather are complementary. Furthermore, it challenges physicians to consider what the best metric is to evaluate treatment success: a symptom score questionnaire, a bladder diary or both?
*WeShareUro by Symptelligence Medical Informatics LLC.