Quality of clinical studies in neurosurgical journals: Signs of improvement over three decades

Object. The aim of this study was to evaluate the quality of clinical studies appearing in neurosurgical journals during three decades. Methods. Clinical studies published in 1982, 1992, and 2002 in Neurosurgery, Journal of Neurosurgery (JNS), and British Journal of Neurosurgery (BJN) were evaluated. The feature study types were categorized as follows: Type 1, prospective randomized controlled trials (PRCTs); Type 2, other prospective studies; Type 3, retrospective case-controlled and cross-sectional studies; and Type 4, case reports. Among a total of 786 articles, the following study types were identified: Type 1, eight (1%); Type 2, 46 (6%); Type 3, 81 (10%); and Type 4, 651 (83%). Overall, the proportion of study types did not differ among journals. Between 1982 and 2002, increases in the proportion of study Types 1 (0 compared with 2%, respectively), 2 (4 compared with 10%, respectively), and 3 (5 compared with 13%, respectively) and decreases in the proportion of study Type 4 (92 compared with 75%, respectively; p <0.001) were apparent only in JNS and Neurosurgery (p <0.01). Between 1982 and 2002, the median number of patients (two compared with 14, respectively) and the mean number of authors per study (3.4 compared with 4.8, respectively) increased (p <0.001). The JNS had a greater mean number of authors per study than the other journals (p <0.001). Conclusions. During the three decades evaluated, case reports remained the predominant study design in these prominent neurosurgical journals, notwithstanding the modest increases in study Types 1 and 2 and the associated escalations in author and patient numbers in the same period.