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Rationalization of interpretation of uroflowmetry for a non-caucasian (Indian) population: conceptual development and validation of volume-normalized flow rate index

Authors


  • Robert Pickard led the peer-review process as the Associate Editor responsible for the paper.
  • Conflict of interest: none.

Abstract

Aims

We intended to define volume-normalized flow rates (cQ; VQI) and to construct and validate uroflow (Q)–volume (V) nomograms in our Indian (non-Caucasian) population.

Methods

Prospective observational study. Participants: Group A, male healthy volunteers 18–45 years without LUTS. Group B, men >18 years with LUTS (IPSS > 7; global QOL > 2). The participants voided in standing on normal-to-strong desire into digital gravimetric uroflowmeter. Data of <50 ml void and intermittent flow was discarded. Reference cQ calculated using (i) Von Garrelts equations (=Q/math formula), (ii) cubic equations (=Q/math formula). Bladder volume (BV) rather than voided volume (VV) was considered for Q–V relation (BV = VV + PVR). VQI derived from present data were compared with the reference-VQI in terms of differences in area-under-curve of receiver operating characteristics. For comparing sensitivity, specificity and predictive values of study nomograms with Caucasian nomograms (Liverpool and Siroky), data of group-A and -B were plotted on each nomogram and no. of observations above and below the cutoffs (defined as equivalent to −1 SD) manually counted.

Results

Total 542 voids of group-A and 465 of group-B included for final analysis. Q–V relation was best described as [Q ∝ BV2.4 ≅ BV2]. The derived VQI (=Q/math formula ≅ Q/math formula) fared significantly superior to reference VQI with VV as denominator. Nomograms, constructed on Q ∝ BV2, were less sensitive but had higher specificity and positive predictive values compared to Caucasian nomograms.

Conclusions

Volume-normalized flow-rate index with BV as denominator (Q/math formula) is has highly discriminative value in screening for voiding dysfunction. Population-specific Q–BV nomograms are more specific and predictive than Caucasian Q–VV nomograms. Neurourol. Urodynam. 33:135–141, 2014. © 2013 Wiley Periodicals, Inc.

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