title: The effect of hormone replacement therapy and tibolone on lipoprotein (a) concentrations in postmenopausal women: A systematic review and meta-analysis.
abstract: OBJECTIVE
  Data on the effect of hormone replacement therapy (HRT) and tibolone on lipoprotein (a) [Lp(a)], an independent risk factor for cardiovascular disease, are heterogeneous and conflicting. Studies of the effect of HRT and tibolone on Lp(a) concentrations in post-menopausal women are reviewed in this meta-analysis.
  
  
  METHODS
  MEDLINE, Scopus, EMBASE and Cochrane databases were searched (up to February 10, 2017). Two researchers identified randomized controlled studies and extracted data. Potential controversies were resolved by a third reviewer.
  
  
  RESULTS
  In 24 eligible studies, HRT caused a significant reduction in Lp(a) concentrations compared with placebo or no treatment [mean relative difference: -20.35%, 95% Confidence Interval (CI): -25.33% to -15.37%, p<0.0001], with significant heterogeneity between studies (I2=98.5%), but without evidence of publication bias. No significant effect was found for tibolone (n=7) (mean relative difference: -23.84%, 95% CI: -63.43% to 15.74%, p=0.238) (I2=98.7%, but without publication bias). Oral estrogen caused a greater reduction in Lp(a) concentrations than transdermal estrogen (n=10) (mean relative difference: 37.66%, 95% CI: 16.84% to 58.48%, p<0.0001), with significant heterogeneity between studies (I2=99%), but no evidence of publication bias. No difference was observed when continuous was compared with cyclical HRT, conventional with low-dose estrogen, and estrogen monotherapy with estrogen combined with progestogen. No difference was observed between HRT and tibolone regarding their effect on Lp(a).
  
  
  CONCLUSIONS
  HRT significantly decreases Lp(a) concentrations, with oral being more effective than transdermal estradiol. The type of HRT, dose of estrogen and addition of progestogen do not seem to modify the Lp(a)-lowering effect of HRT.
authors.affiliation: Unit of Reproductive Endocrinology, First Department of Obstetrics and Gynecology, Medical School, Aristotle University of Thessaloniki, Greece. Electronic address: anagnwstis.pan@yahoo.gr.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Anagnostis
authors.affiliation: Center for Health Services Management and Evaluation, Department of Nursing, National and Kapodistrian University of Athens, Greece.
authors.forename: Petros
authors.initials: P
authors.lastname: Galanis
authors.affiliation: Unit of Reproductive Endocrinology, First Department of Obstetrics and Gynecology, Medical School, Aristotle University of Thessaloniki, Greece.
authors.forename: Vasileia
authors.initials: V
authors.lastname: Chatzistergiou
authors.affiliation: National Heart and Lung Institute, Imperial College London, Royal Brompton and Harefield NHS Foundation Trust, London SW3 6NP, UK.
authors.forename: John C
authors.initials: JC
authors.lastname: Stevenson
authors.affiliation: Diabetes Endocrinology and Metabolic Medicine, Faculty of Medicine, Imperial College London,St. Mary's Campus, London, UK.
authors.forename: Ian F
authors.initials: IF
authors.lastname: Godsland
authors.affiliation: Second Department of Obstetrics and Gynecology, National and Kapodistrian University of Athens, Greece.
authors.forename: Irene
authors.initials: I
authors.lastname: Lambrinoudaki
authors.affiliation: Health Policy and Management Department, Open University of Cyprus, Cyprus.
authors.forename: Mamas
authors.initials: M
authors.lastname: Theodorou
authors.affiliation: Unit of Reproductive Endocrinology, First Department of Obstetrics and Gynecology, Medical School, Aristotle University of Thessaloniki, Greece.
authors.forename: Dimitrios G
authors.initials: DG
authors.lastname: Goulis
mesh_terms: D000279:Administration, Cutaneous; D000284:Administration, Oral; D002318:Cardiovascular Diseases / Q000097:blood; D004958:Estradiol / Q000627:therapeutic use*; D020847:Estrogen Receptor Modulators / Q000627:therapeutic use*; D015914:Estrogen Replacement Therapy / Q000379:methods*; D004967:Estrogens / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D017270:Lipoprotein(a) / Q000097:blood*; D009652:Norpregnenes / Q000627:therapeutic use*; D017698:Postmenopause / Q000097:blood*; D011372:Progestins / Q000627:therapeutic use*; D012307:Risk Factors
chemical_list: D020847:Estrogen Receptor Modulators; D004967:Estrogens; D017270:Lipoprotein(a); D009652:Norpregnenes; D011372:Progestins; D004958:Estradiol; C027385:tibolone
keywords: Cardiovascular risk; Lipoprotein (a); Menopause; Meta-analysis; Postmenopausal women