Vatten L J, Holmen J, Krüger O, Forsén L, Tverdal A
Department of Environmental and Community Medicine, University Medical Center, Trondheim, Norway.
Epidemiology. 1995 Jan;6(1):70-3.
Several studies have shown that low blood pressure in individuals age 65 years and older is related to increased overall mortality. We hypothesize that this association is secondary to serious underlying illness, which has caused blood pressure reduction and, subsequently, has increased the risk of dying. Our study population was comprised of individuals age 20 years and older in the county of Nord Trøndelag in Norway, who were studied in a general health survey between 1984 and 1986. We had measurements of blood pressure, blood glucose, weight, height, and other information for 9,732 women and 8,290 men age 65 years or older. During approximately 6 years of follow-up, 2,122 women and 2,578 men died. For both genders, low systolic pressure was not associated with increased mortality, and the mortality curve did not display a J-shaped relation, after adjustment for age, marital status, body mass index, blood glucose, self-assessed health, use of antihypertensive medication, and history of diabetes and cardiovascular diseases. For diastolic pressure, however, women in the lowest category (< 75 mmHg) had an adjusted mortality rate ratio of 1.21 (95% confidence limits = 1.05, 1.39), compared with reference women (80-87 mmHg). Among men, the analogous mortality rate ratio was 1.16 (95% confidence limits = 1.02, 1.31). To reduce further the potential confounding between diastolic pressure and underlying illness, we excluded users of antihypertensive medication as well as the 2 first years of follow-up. After these procedures, the J-shaped mortality curve was not present among women, and it was substantially reduced among men. Thus, the results for both men and women indicated that the age-adjusted J-shaped relation between diastolic blood pressure and mortality was confounded with indicators of ill health, and that the often-found association between low diastolic blood pressure and increased mortality is indirect, possibly caused by serious underlying disease.
多项研究表明，65岁及以上人群的低血压与总体死亡率增加有关。我们推测这种关联是严重潜在疾病的继发结果，该疾病导致血压降低，进而增加了死亡风险。我们的研究对象包括挪威北特伦德拉格郡20岁及以上的人群，他们在1984年至1986年期间接受了一次普通健康调查。我们获取了9732名65岁及以上女性和8290名65岁及以上男性的血压、血糖、体重、身高及其他信息。在大约6年的随访期内，2122名女性和2578名男性死亡。对于两性而言，在调整了年龄、婚姻状况、体重指数、血糖、自我评估的健康状况、抗高血压药物的使用以及糖尿病和心血管疾病史之后，收缩压降低与死亡率增加无关，且死亡率曲线未呈现J形关系。然而，对于舒张压，最低类别（<75 mmHg）的女性调整后的死亡率比值为1.21（95%置信区间 = 1.05, 1.39），而参照女性为（80 - 87 mmHg）。在男性中，类似的死亡率比值为1.16（95%置信区间 = 1.02, 1.31）。为了进一步减少舒张压与潜在疾病之间的潜在混杂因素，我们排除了抗高血压药物使用者以及随访的前两年。经过这些步骤后，女性中未出现J形死亡率曲线，男性中的该曲线也大幅降低。因此，男性和女性的结果均表明，舒张压与死亡率之间经年龄调整后的J形关系与健康不佳指标相混杂，且经常发现的低舒张压与死亡率增加之间的关联是间接的，可能由严重的潜在疾病引起。
