A Double-Blind Placebo-Controlled Trial of Maca Root as Treatment for Antidepressant-Induced Sexual Dysfunction in Women

Table 1

Subjects reaching four remission criteria, based on both MGH-SFQ^a and ASEX^b, by treatment and menopausal status.

Remission; criterion	Menopausal; status	Maca		Placebo		Maca/placebo; relative; risk^d	Maca/placebo; odds ratio; (95% CI)^e	Number needed to treat (NNT)^f
			(%)^c remitted		(%)^c remitted
ASEX ≤10	Before	14	1 (7.14)	16	1 (6.25)	1.143	1.154 (0.065–20.342)	112
	After	7	1 (14.29)	5	0 (0.0)	—	5.553 (0.104–295.862)	7
	Total	21	2 (9.52)	21	1 (4.76)	2.000	2.105 (0.176–25.172)	21
ASEX ≤8	Before	14	0 (0.0)	16	0 (0.0)	—	—	—
	After	7	0 (0.0)	5	0 (0.0)	—	—	—
	Total	21	0 (0.0)	21	0 (0.0)	—	—	—
MGH-SFQ ≤12	Before	13^h	2 (15.38)	15^i	4 (26.67)	0.577	0.500 (0.075–3.316)	9 (NNH)^g
	After	7	4 (57.14)	5	1 (20.00)	2.857	5.333 (0.375–75.779)	2
	Total	20	6 (30.00)	20	4 (20.00)	1.500	1.714 (0.400–7.340)	10
MGH-SFQ ≤8	Before	14	1 (7.14)	15^i	1 (6.67)	1.071	1.077 (0.061–19.047)	210
	After	7	1 (14.29)	5	0 (0.0)	—	5.553 (0.104–295.862)	7
	Total	21	2 (9.52)	20	1 (5.00)	1.905	2.000 (0.167–23.962)	23

MGH-SFQ: Massachusetts General Hospital-Sexual Functioning Questionnaire.
^bASEX: Arizona Sexual Experience Scale.
^cPercentages are shown to 2 decimal places, for greater accuracy in computing relative risk, odds ratio, and NNT.
^dRelative risk is calculated by maca % remitted/placebo % remitted.
^eAn odds ratio is calculated by (maca % remitted/% nonremitted)/(placebo % remitted/% nonremitted). Odd ratios and their confidence intervals were obtained by entering the cell counts (number remitted/not) into a calculator available at http://www.hutchon.net/ConfidOR.htm. For values with a zero in any cell, an on-line calculator using the null hypothesis (http://www.hutchon.net/ConfidORnulhypo.htm) was used; caution is urged in interpreting these values. All odds ratio and 95% confidence interval values involving nonzero cells were confirmed against a second on-line calculator available at http://faculty.vassar.edu/lowry/odds2x2.html. The odds ratio is mathematically important but difficult to interpret. For that reason, number needed to treat (NNT) is often included as a more clinically interpretable statistic (see below).
^fNumber needed to treat (NNT) is calculated by 1/(maca % remitters − placebo % remitters). (The conservative convention is to round up, for anything but an even whole number.) Because the odds ratio is difficult to interpret, NNT is becoming the accepted “effect size” measure for binary outcomes. It is directly interpretable as the number of people you need to treat with maca in order to have one more remitter than in the placebo group, that is, the number needed to treat to have one more person reaching the benefit criterion. A convention is emerging, where 5 is considered a “good” number, but this can vary depending on the risk/benefit and cost associated with the active treatment.
^gBecause the remission rate is lower for maca than for placebo, results are presented as the number needed to harm (NNH), which is interpreted as the number of people you need to treat with maca in order to have one more failure to remit than in the placebo group.
^hOne subject is not included for either MGH-SFQ remission criterion because baseline MGH-SFQ total = 8.
ⁱOne subject is not included for MGH-SFQ ≤12 remission criterion because baseline MGH-SFq total = 12.