G Tuncer proposed the concept, designed the study, wrote the protocol and managed the study. G Tuncer, S Surme, IY Nakir and M Yazla, performed the statistics, interpreted the data and wrote the manuscript. S Surme, A Buyukyazgan, AK Cinar, B Copur, E Zerdali, G Tuncer, H Balli, IY Nakir, M Yazla, Y Kurekci were involved in collecting the data. MM Sonmez, S S-Yavuz, F Pehlivanoglu, G Sengoz performed a critical review of the manuscript. All authors provided inputs for revision of the manuscript. S Surme communicated with the journal and addressed comments from reviewers. All authors contributed to data acquisition, data analysis or data interpretation and reviewed and approved the final version.