Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada.
J Cardiovasc Electrophysiol. 2010 Dec;21(12):1375-80. doi: 10.1111/j.1540-8167.2010.01848.x.
accurate selection of patients for vasovagal syncope studies requires strong risk stratification and knowledge of the natural history of syncope. We aimed to test the hypothesis that recent history of vasovagal syncope compared to distant history better predicts subsequent recurrence of syncope.
in all, 208 subjects with a positive tilt test and ≥ 3 lifetime syncope spells were followed for 1 year. Syncope episodes in the preceding year and total historical spells were compared for their ability to predict a syncope recurrence using the criteria of optimal statistical significance, best linear separation of risk populations, and impact on power calculations. The number of vasovagal syncope spells in the preceding year better predicted syncope recurrence when compared to total number of historical spells (likelihood ratio statistic 28.4, P < 0.0001; versus 20.4, P = 0.001), and showed a substantial effect as the number of syncope events increased. For example, syncope recurred in 22% of those with <2 spells in the previous year compared to 69% in those with >6 spells. A history of no syncope compared to any syncope in the preceding year was associated with a 1-year probability of 7% versus 46% for syncope recurrence. A study designed to detect a 50% decrease in syncope recurrence at P = 0.05 with 80% power would require 159 patients with at least 3 lifetime spells, and only 108 patients with at least 3 spells in the previous year.
the number of syncope events in the year preceding clinical evaluation is the best predictor of syncope recurrence.
准确选择血管迷走性晕厥研究的患者需要进行强有力的风险分层，并了解晕厥的自然病史。我们旨在检验这样一个假设，即与遥远的病史相比，近期血管迷走性晕厥史能更好地预测随后晕厥的复发。
共有 208 名阳性倾斜试验和≥3 次一生中晕厥发作的患者接受了 1 年的随访。在过去的 1 年中，比较了晕厥发作史和总晕厥发作史，以确定它们预测晕厥复发的能力，采用最佳统计学意义、风险人群最佳线性分离和对功效计算的影响的标准。与总历史发作次数相比，前一年的血管迷走性晕厥发作次数更好地预测了晕厥复发（似然比统计量 28.4，P<0.0001；与 20.4，P=0.001），并且随着晕厥事件数量的增加，其效果显著。例如，在前一年有<2 次晕厥发作的患者中，有 22%的患者复发，而在前一年有>6 次晕厥发作的患者中，有 69%的患者复发。与前一年无晕厥相比，有任何晕厥史的患者在 1 年内发生晕厥的概率分别为 7%和 46%。如果要设计一项研究，以 80%的功效和 P=0.05 的显著性水平检测晕厥复发率降低 50%，则需要至少 159 名至少有 3 次一生中晕厥发作的患者，而仅需要至少有前一年 3 次晕厥发作的 108 名患者。
临床评估前一年的晕厥发作次数是预测晕厥复发的最佳指标。
