Title: Reply - Letter to the Editor - Meta-analysis of L-carnitine supplementation on lipid profile and glycemic control: inadequate search strategy and other methodological issues
Abstract: We are pleased to submit a response to the letter to the editor you have received from Raeisi-Dehkordi et al. (YCLNU-S-20-00293): 1.We excluded the articles that were done by participating patients with kidney and liver failure and we did not include those in the search strategy using the MeSH term [ [1] Asadi M. Rahimlou M. Shishehbor F. Mansoori A. The effect of l-carnitine supplementation on lipid profile and glycaemic control in adults with cardiovascular risk factors: a systematic review and meta-analysis of randomized controlled clinical trials. Clin Nutr. 2020; 39: 110-122 Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar ]. Because several systematic review and meta-analysis were perfumed by including studies on kidney diseases exclusively [ 2 Chen Y. Abbate M. Tang L. Cai G. Gong Z. Wei R. et al. L-Carnitine supplementation for adults with end-stage kidney disease requiring maintenance hemodialysis: a systematic review and meta-analysis. Am J Clin Nutr. 2014; 99: 408-422 Crossref PubMed Scopus (52) Google Scholar , 3 Gholipur-Shahraki T. Feizi A. Mortazavi M. Badri S. Effects of carnitine on nutritional parameters in patients with chronic Kidney disease: an updated systematic review and meta-analysis. J Res Pharm Pract. 2018; 7: 57 Crossref PubMed Google Scholar , 4 Huang H. Song L. Zhang H. Zhang H. Zhang J. Zhao W. Influence of L-carnitine supplementation on serum lipid profile in hemodialysis patients: a systematic review and meta-analysis. Kidney Blood Pres Res. 2013; 38: 31-41 Crossref PubMed Scopus (26) Google Scholar , 5 Yang S.-k. Xiao L. Song P.-a. Xu X. Liu F.-y. Sun L. Effect of L-carnitine therapy on patients in maintenance hemodialysis: a systematic review and meta-analysis. J Nephrol. 2014; 27: 317-329 Crossref PubMed Scopus (27) Google Scholar ]. 2.We included studies with participating adults with cardiovascular risk factors. Thus, we excluded studies with healthy metabolic adults [ [6] Delaš I. Dražić T. Čačić-Hribljan M. Sanković K. Effect of L-carnitine supplementation on some biochemical parameters in blood serum of sedentary population. Croat Chem Acta. 2008; 81: 163-168 Google Scholar ] and also mixed supplementation [ [7] Bloomer R.J. Fisher-Wellman K.H. Tucker P.S. Effect of oral acetyl L-carnitine arginate on resting and postprandial blood biomarkers in pre-diabetics. Nutr Metab. 2009; 6: 25 Crossref Scopus (28) Google Scholar ]. However, five studies were missed in the hand searching that we will include those in the updated meta-analysis [ 8 Alavinejad P. Zakerkish M. Hajiani E. Hashemi S.J. Chobineh M. Moghaddam E.K. Evaluation of L-carnitine efficacy in the treatment of non-alcoholic fatty liver disease among diabetic patients: a randomized double blind pilot study. J Gastroenterol Hepatol Res. 2016; 5: 2191-2195 Crossref Google Scholar , 9 Hakimi M. Sheikholeslami Vatani D. Alimohammadi M. Effect of concurrent training with ingested of lcarnitine supplementation on hormonal changes, lipid profile and body composition in obese men. J Urmia Univ Med Sci. 2015; 26: 185-193 Google Scholar , 10 Liang Y. Li Y. Shan J. Yu B. Ho Z. The effects of oral L-carnitine treatment on blood lipid metabolism and the body fat content in the diabetic patient. Asia Pac J Clin Nutr. 1998; 7: 192-195 PubMed Google Scholar , 11 Malaguarnera M. Cammalleri L. Gargante M.P. Vacante M. Colonna V. Motta M. L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial. Am J Clin Nutr. 2007; 86: 1738-1744 Abstract Full Text Full Text PDF PubMed Scopus (97) Google Scholar , 12 Pistone G. Marino A.D. Leotta C. Dell'Arte S. Finocchiaro G. Malaguarnera M. Levocarnitine administration in elderly subjects with rapid muscle fatigue. Drugs Aging. 2003; 20: 761-767 Crossref PubMed Scopus (71) Google Scholar ]. 3.In the search strategy in PubMed, we searched l-carnitine keywords in combination with cardiovascular risk factors “AND” cardiovascular diseases that our mean was a combination of L-carnitine keywords with one of those. Thus, it was better to use “OR” instead of “AND” to avoid misunderstanding. However, the search was done correctly. The number of articles in the initial search is low because the search was restricted to the clinical trials and we have mentioned it in the search strategy section of the article. 4.We didn't search for keywords with quotation marks. We just were written keywords with quotation marks in the table to be clear. Therefore, there was no limitation in the search strategy. 5.Unfortunately, about calculating the mean change of total cholesterol (TC) in the study by Solfrizzi et al. [ [13] Solfrizzi V. Capurso C. Colacicco A.M. D'Introno A. Fontana C. Capurso S.A. et al. Efficacy and tolerability of combined treatment with L-carnitine and simvastatin in lowering lipoprotein (a) serum levels in patients with type 2 diabetes mellitus. Atherosclerosis. 2006; 188: 455-461 Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar ] an error has happened. However, sensitivity analysis on TC was showed that leaving this study had no significant effect on the pooled effect size of TC. A correction about this error will be considered in the updated meta-analysis.
Publication Year: 2020
Publication Date: 2020-04-21
Language: en
Type: letter
Indexed In: ['crossref', 'pubmed']
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