title: Reporting quality of N-of-1 trials published between 1985 and 2013: a systematic review.
abstract: To evaluate the quality of reporting of single-patient (N-of-1) trials published in the medical literature based on the CONSORT Extension for N-of-1 Trials (CENT) statement and to examine factors that influence reporting quality in these trials.
  
  
  
  Through a search of 10 electronic databases, we identified N-of-1 trials in clinical medicine published between January 1, 1985, and December 31, 2013. Two reviewers screened articles for eligibility and independently extracted data. Quality assessment was performed using the CENT statement. Discrepancies were resolved by consensus.
  
  
  
  We identified 112 eligible N-of-1 trials published in 87 journals and involving a total of 2,278 patients. Overall, kappa agreement between the two evaluators for compliance with CENT criteria was 0.80 (95% confidence interval: 0.79, 0.82). Trials assessed pharmacology and therapeutics (87%), behavior (11%), or diagnosis (2%). Although 87% of articles described the trial design (including the planned number of subjects and length of treatment period), the median percentage of specific CENT elements reported in the Methods was 41% (range, 16-87%), and the median percentage in the Results was 38% (range, 32-93%). First authors were predominantly from North America (46%), Europe (29%), and Australia (17%). Quality of reporting was higher in articles published in journals with relatively high-impact factors (P = 0.004).
  
  
  
  The quality of reporting of published N-of-1 trials is variable and in need of improvement. Because the CENT guidelines were not published until near the end of the period of this review, these results represent a baseline from which improvement may be expected in the future.
authors.affiliation: Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, No. 199 Donggang West Road, Chengguan District, Lanzhou, 730000, China; Key Laboratory of Evidence Based Medicine and Knowledge Translation of Gansu Province, No. 199 Donggang West Road, Chengguan District, Lanzhou, 730000, China; Office for Cancer Screening Program in Urban China, Cancer Hospital, Chinese Academy of Medical Sciences, National Cancer Center of China, No.17 Panjiayuan Nanli, Chaoyang District, Beijing, 100021, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Li
authors.affiliation: Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.affiliation: Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Salima
authors.initials: S
authors.lastname: Punja
authors.affiliation: Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, No. 199 Donggang West Road, Chengguan District, Lanzhou, 730000, China; Key Laboratory of Evidence Based Medicine and Knowledge Translation of Gansu Province, No. 199 Donggang West Road, Chengguan District, Lanzhou, 730000, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Ma
authors.affiliation: Complementary and Alternative Research and Education (CARE) Program, Department of Pediatrics and School of Public Health, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Sunita
authors.initials: S
authors.lastname: Vohra
authors.affiliation: Department of Psychiatry, Columbia University, New York, USA; Department of Biostatistics, Columbia University, New York, USA.
authors.forename: Naihua
authors.initials: N
authors.lastname: Duan
authors.affiliation: Center for Clinical Epidemiology and Biostatistics and Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Gabler
authors.affiliation: Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, No. 199 Donggang West Road, Chengguan District, Lanzhou, 730000, China; Key Laboratory of Evidence Based Medicine and Knowledge Translation of Gansu Province, No. 199 Donggang West Road, Chengguan District, Lanzhou, 730000, China. Electronic address: yangkh2006@163.com.
authors.forename: Kehu
authors.initials: K
authors.lastname: Yang
authors.affiliation: Department of Internal Medicine and Center for Healthcare Policy and Research, University of California Davis, 4150 V Street, Suite 2400 PSSB, Sacramento, CA 95817, USA. Electronic address: rlkravitz@ucdavis.edu.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Kravitz
mesh_terms: D035843:Biomedical Research / Q000592:standards* / Q000639:trends; D002986:Clinical Trials as Topic / Q000592:standards*; D000068598:Data Accuracy; D005544:Forecasting; D017408:Guidelines as Topic; D006801:Humans; D011643:Publishing / Q000592:standards* / Q000639:trends; D012107:Research Design / Q000592:standards* / Q000639:trends; D058028:Research Report / Q000592:standards* / Q000639:trends; D009626:Terminology as Topic
keywords: CONSORT guidelines; Chronic Disease; Reporting quality; Single-patient (N-of-1) trials; Therapy Comparative Effectiveness Research