Delgado Rodríguez M, Ruiz-Canela M, de Irala-Estévez J, Llorca Díaz J, Martínez-González M A
Cátedra de Medicina Preventiva y Salud Pública, Departamento de Ciencias de la Salud, Universidad de Jaén, Paraje de las Lagunillas, s/n. 23071 Jaén.
Rev Clin Esp. 2001 Aug;201(8):437-43.
The assessment of the methodological quality of controlled clinical trials (CCTs) carried out in Spain and published in international journals and the comparison with those published in widely read general journals of medicine (N Engl J Med, Lancet, JAMA, BMJ) may help establishing their limitations and improving quality in future studies.
Search in Medline of CCTs. Studies were evaluated according to a structured questionnaire (J Clin Epidemiol 1992; 45:225-265). The odds ratio and their 95% confidence intervals were used to compare spanish studies with the remaining studies. The following variables were considered as confounders and controlled for by logistic regression analysis: number of participating centers, sample size, funding source, and the inclusion of epidemiologists in the research team. The journal's impact factor was taken into account.
Spanish CTTs had a smaller sample size, were mostly monocentric, reported les frequently the source of funding, and exhibited a lower participation of epidemiologists. The informed consent and the approval by the ethics committee were more frequently omitted. The major methodological differences with the other studies were: lack of pre-study sample size and statistical power estimation, lack of inclusion criteria, poor explanation of patients' flow in the selection process, lack of explanation for unmasked procedures, poor description of methods to assess intervention compliance, under-reporting confidence intervals, and less frequent use of the intention-to-treat principle. The quality score of spanish studies was lower (9.4 +/- 1.7 vs 10.7 +/- 1.5; p < 0.001). These limitations improved with higher journal's impact factor, the quality score was 8.5 in journals with an impact factor < 1.5, and 10.6 in those with an impact factor > 4.5. This last figure is almost identical to the average of CCTs published in general journals of medicine.
Most spanish studies achieved a good quality score. Nevertheless, there are still issues which can be overcome easily. If this goal is achieved, the results will obtain a higher repercussion, as a better quality is observed in those published in journals with the highest impact factor.
评估在西班牙开展并发表于国际期刊的对照临床试验（CCT）的方法学质量，并与发表于广泛阅读的普通医学期刊（《新英格兰医学杂志》《柳叶刀》《美国医学会杂志》《英国医学杂志》）上的研究进行比较，可能有助于明确其局限性并提高未来研究的质量。
在Medline中检索CCT。根据一份结构化问卷（《临床流行病学杂志》1992年；45：225 - 265）对研究进行评估。使用比值比及其95%置信区间将西班牙的研究与其他研究进行比较。以下变量被视为混杂因素，并通过逻辑回归分析进行控制：参与中心数量、样本量、资金来源以及研究团队中流行病学家的纳入情况。考虑了期刊的影响因子。
西班牙的CTT样本量较小，大多为单中心研究，较少报告资金来源，且流行病学家的参与度较低。更频繁地省略了知情同意和伦理委员会的批准。与其他研究的主要方法学差异包括：缺乏研究前样本量和统计效力估计、缺乏纳入标准、对患者在选择过程中的流程解释不佳、对非盲法程序缺乏解释、对评估干预依从性的方法描述不佳、置信区间报告不足以及较少使用意向性分析原则。西班牙研究的质量得分较低（9.4 ± 1.7 vs 10.7 ± 1.5；p < 0.001）。随着期刊影响因子的提高，这些局限性有所改善，影响因子<1.5的期刊中质量得分为8.5，影响因子>4.5的期刊中质量得分为10.6。最后这个数字几乎与普通医学期刊上发表的CCT的平均值相同。
大多数西班牙研究获得了良好的质量得分。然而，仍有一些问题可以轻松克服。如果实现这一目标，结果将产生更大的反响，因为在影响因子最高的期刊上发表的研究质量更高。
