Table 1.

Summary of findings of carnitine compared to placebo or no treatment for idiopathic male infertility.

Outcomes	Anticipated absolute effects (95% CI)			RR (95% CI)	Participants in studies		Certainty of evidence
	Risk with placebo or no treatment, range	Risk with carnitine
		Value	Range		n	Studies	Evidence	Grade
Sperm concentration	0.8–33.73 million/mL	MD 2.7 million/mL higher	2.04 lower to 7.44 higher	–	438	6 RCTs	⊕⊝⊝⊝	VERY LOWa,b,c
Total sperm motility	3.3–43.4%	MD 10.72% higher	3.94 higher to 17.5 higher	–	459	7 RCTs	⊕⊕⊝⊝	LOWa,c
Progressive sperm motility	4–24.41%	MD 9.82% higher	2.01 higher to 17.62 higher	–	231	3 RCTs	⊕⊕⊝⊝	LOWa,c
Normal sperm morphology	1.39–32.73%	MD 2.41% higher	0.79 higher to 4.03 higher	–	438	6 RCTs	⊕⊕⊝⊝	LOWa,c
Clinical pregnancy
Study population	113 per 1000	116 per 1000	61–221	1.03 (0.54–1.96)	301	5 RCTs	⊕⊕⊝⊝	LOWa,b

The population was men with abnormal semen characteristics. The intervention was l-carnitine and/or l-acetylcarnitine. The table compares placebo or no treatment. The outcomes measured were semen analysis parameters; clinical pregnancy; adverse events in a clinic or hospital.

^aLack of blinding; ^bCrosses the line of no effect; ^cHiggins’s I² test >50%.