Lab-based semen parameters as predictors of long-term health in men-a systematic review.

Study question: Can semen parameters predict long-term health outcomes in men?

Summary answer: There is a lack of evidence to suggest a higher risk of comorbidities in men with poor semen concentration.

What is known already: Male infertility has been long associated with a higher mortality risk and possibly higher chance of developing comorbidities but there has been less focus on semen analysis as a potential predictive factor.

Study design size duration: We searched PubMed/MEDLINE, EMBASE, and EBM databases from inception to December 2023. MESH term strategy: heading 1 ('OR', semen analysis, sperm count, sperm parameter*, male infertility, azoospermia, aspermia, oligospermia, teratozoospermia, asthenozoospermia) 'AND' heading 2 ('OR', morbidity, mortality, diabetes, cancer, cardiovascular, death, hypertension, stroke, long-term health). We included all studies that analyzed the risk of mortality and/or future development of comorbidities in men with at least one semen analysis. Case series and reviews were excluded.

Participants/materials setting methods: A narrative synthesis was done for all studies and meta-analysis where possible. Odds ratio (ORs) (95% CI, P-value) were calculated for all men with one suboptimal semen parameter and associated with the risk of a particular outcome. The risk of bias was assessed with QUADAS-2.

Main results and the role of chance: Twenty-one studies were finally included. There was either a high or unclear risk of bias in all studies. The results only allowed for meta-analysis on categories of sperm concentration. We found a 2-fold increase in mortality risk in azoospermic men compared to oligospermic (OR 1.96, 95% CI: 1.29-2.96) and normozoospermic (OR 2.00, 95% CI: 1.23-3.25) groups, but not in oligospermic compared to normozoospermic (OR 1.04, 95% CI: 0.52-2.09). There was no difference in risk of cardiovascular disease in any of the sperm concentration groups (azoospermic-oligospermic OR 0.94, 95% CI: 0.74-1.20, azoospermic-normozoospermic OR 1.11, 95% CI: 0.71-1.75, and oligospermic-normozoospermic OR 1.12, 95% CI: 0.80-1.55). OR for diabetes in azoospermic men was higher only compared to oligospermic (OR 2.16, 95% CI: 1.55-3.01). The risk of all-site cancer was higher in azoospermic men compared to oligospermic (OR 2.16, 95% CI: 1.55-3.01) and normozoospermic (OR 2.18, 95% CI: 1.20-3.96). Only azoospermic men might be at higher risk of testicular cancer when compared to men with normal sperm concentration (OR 1.80, 95% CI: 1.12-2.89).

Limitations reasons for caution: Although our pooled analysis shows an increased risk of mortality and all-site cancer risk in azoospermic men, the results show a lack of evidence to suggest a higher risk of comorbidities in men with poor semen concentration. Given the limited available data, the nature of the studies, and the high risk of bias, the results should be interpreted with caution.

Wider implications of the findings: There is not enough data to confirm the usability of semen analysis as a predictor of poor long-term health in men, especially within the general population.

Study funding/competing interests: No funding was obtained for this study. A.M. has received funding from Merck Serono, Ferring, Gedeon Richter, Pharmasure, and Cook Medical to attend medical conferences; has been a participant in an advisory board for Ferring; and has given an invited lecture for a Merck Serono advisory board. S.N. has received funding for medical conference attendance from Ferring and Cook Medical.

Registration number: PROSPERO No. CRD42024507563.