Regression to the mean occurs in measuring peak urinary flow.
OBJECTIVE
To investigate the anomalous rises in maximum urinary flow rates seen in a prostate-diagnostic clinic.


METHODS
The study comprised 1994 men aged 40-79 years registered at five health centres in Central Scotland, participating in a study of the natural history of benign prostatic hyperplasia (BPH), who completed a urodynamic assessment on up to three occasions: in the community, on referral to a prostate-diagnostic clinic and at a one-year follow-up.


RESULTS
Subjects referred to the diagnostic clinic on the basis of maximum flow rate (Qmax < 15 mL/s) and/or urinary symptomatology showed a mean increase in Qmax (P < 0.001) when tested at the clinic and at the one-year follow-up. In health centres which referred men to the clinic with no pre-selection, there were no significant changes in Qmax.


CONCLUSIONS
Regression to the mean occurs when patients are selected on the basis of a low Qmax. The use of isolated low values of Qmax in the process of diagnosing BPH should be avoided.
Department of Public Health Sciences, University of Edinburgh Medical School, UK.
R J
RJ
Prescott
W M
WM
Garraway
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011470:Prostatic Hyperplasia / Q000175:diagnosis / Q000503:physiopathology*; D012044:Regression Analysis; D014554:Urination; D014563:Urodynamics