Geometric mean IELT and premature ejaculation: appropriate statistics to avoid overestimation of treatment efficacy.
BACKGROUND
The intravaginal ejaculation latency time (IELT) behaves in a skewed manner and needs the appropriate statistics for correct interpretation of treatment results.


OBJECTIVE
To explain the rightful use of geometrical mean IELT values and the fold increase of the geometric mean IELT because of the positively skewed IELT distribution.


METHODS
Linking theoretical arguments to the outcome of several selective serotonin reuptake inhibitor and modern antidepressant study results.


METHODS
Geometric mean IELT and fold increase of geometrical mean IELT.


RESULTS
Log-transforming each separate IELT measurement of each individual man is the basis for the calculation of the geometric mean IELT. A drug-induced positively skewed IELT distribution necessitates the calculation of the geometric mean IELTs at baseline and during drug treatment. In a positively skewed IELT distribution, the use of the "arithmetic" mean IELT risks an overestimation of the drug-induced ejaculation delay as the mean IELT is always higher than the geometric mean IELT. Strong ejaculation-delaying drugs give rise to a strong positively skewed IELT distribution, whereas weak ejaculation-delaying drugs give rise to (much) less skewed IELT distributions. Ejaculation delay is expressed in fold increase of the geometric mean IELT.


CONCLUSIONS
Drug-induced ejaculatory performance discloses a positively skewed IELT distribution, requiring the use of the geometric mean IELT and the fold increase of the geometric mean IELT.
Waldinger
Marcel D
MD
Department of Psychiatry and Neurosexology, Haga Hospital Leyenburg, The Hague, The Netherlands. md@waldinger.demon.nl
Zwinderman
Aeilko H
AH
Olivier
Berend
B
Schweitzer
Dave H
DH
D000928:Antidepressive Agents / Q000627:therapeutic use*; D003075:Coitus; D003627:Data Interpretation, Statistical; D004542:Ejaculation / Q000187:drug effects*; D005473:Fluoxetine / Q000627:therapeutic use; D016666:Fluvoxamine / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008803:Mianserin / Q000031:analogs & derivatives / Q000627:therapeutic use; D000078785:Mirtazapine; D008954:Models, Biological; D010879:Piperazines; D011930:Reaction Time / Q000187:drug effects; D012107:Research Design; D012680:Sensitivity and Specificity; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use*; D020280:Sertraline / Q000627:therapeutic use; D012735:Sexual Dysfunction, Physiological / Q000188:drug therapy*; D016896:Treatment Outcome; D014230:Triazoles / Q000627:therapeutic use
D000928:Antidepressive Agents; D005473:Fluoxetine; D016666:Fluvoxamine; D008803:Mianserin; D000078785:Mirtazapine; D010879:Piperazines; D017367:Selective Serotonin Reuptake Inhibitors; D020280:Sertraline; D014230:Triazoles; C051752:nefazodone