Moll Carina, Gessler Ursula, Bartsch Stephanie, El-Sayeh Hany George, Fenton Mark, Adams Clive Elliott
Schule fuer Medizinische Dokumentation, Universitaetklinikum Ulm, Academie fuer Medizinische Berufe, Ulm, 89070, Germany.
BMC Psychiatry. 2003 Dec 5;3:18. doi: 10.1186/1471-244X-3-18.
The 5000 randomised controlled trials (RCTs) in the Cochrane Schizophrenia Group's database affords an opportunity to research for variables related to the differences between nations of their output of schizophrenia trials.
Ecological study--investigating the relationship between four economic/demographic variables and number of schizophrenia RCTs per country. The variable with closest correlation was used to predict the expected number of studies.
GDP closely correlated with schizophrenia trial output, with 76% of the total variation about the Y explained by the regression line (r = 0.87, 95% CI 0.79 to 0.92, r2 = 0.76). Many countries have a strong tradition of schizophrenia trials, exceeding their predicted output. All nations with no identified trial output had GDPs that predicted zero trial activity. Several nations with relatively small GDPs are, nevertheless, highly productive of trials. Some wealthy countries seem either not to have produced the expected number of randomised trials or not to have disseminated them to the English-speaking world.
This hypothesis-generating study could not investigate causal relationships, but suggests, that for those seeking all relevant studies, expending effort searching the scientific literature of Germany, Italy, France, Brazil and Japan may be a good investment.
Cochrane精神分裂症研究小组数据库中的5000项随机对照试验（RCT）为研究与各国精神分裂症试验产出差异相关的变量提供了契机。
生态研究——调查四个经济/人口统计学变量与每个国家精神分裂症RCT数量之间的关系。使用相关性最密切的变量来预测预期的研究数量。
国内生产总值（GDP）与精神分裂症试验产出密切相关，回归线解释了Y总变异的76%（r = 0.87，95%置信区间0.79至0.92，r2 = 0.76）。许多国家有进行精神分裂症试验的悠久传统，其试验产出超过预期。所有未确定有试验产出的国家，其GDP预测的试验活动为零。然而，一些GDP相对较小的国家试验产出却很高。一些富裕国家似乎要么没有进行预期数量的随机试验，要么没有将其传播到英语国家。
这项产生假设的研究无法调查因果关系，但表明，对于那些寻求所有相关研究的人来说，花费精力检索德国、意大利、法国、巴西和日本的科学文献可能是一项不错的投资。
