Prevalence of posttraumatic stress disorder (PTSD) defined according to the American Psychiatric Association's Diagnostic and Statistical Manual fifth edition (DSM‐5; 2013) and fourth edition (DSM‐IV; 1994) was compared in a national sample of U.S. adults (N = 2,953) recruited from an online panel. Exposure to traumatic events, PTSD symptoms, and functional impairment were assessed online using a highly structured, self‐administered survey. Traumatic event exposure using DSM‐5 criteria was high (89.7%), and exposure to multiple traumatic event types was the norm. PTSD caseness was determined using Same Event (i.e., all symptom criteria met to the same event type) and Composite Event (i.e., symptom criteria met to a combination of event types) definitions. Lifetime, past‐12‐month, and past 6‐month PTSD prevalence using the Same Event definition for DSM‐5 was 8.3%, 4.7%, and 3.8% respectively. All 6 DSM‐5 prevalence estimates were slightly lower than their DSM‐IV counterparts, although only 2 of these differences were statistically significant. DSM‐5 PTSD prevalence was higher among women than among men, and prevalence increased with greater traumatic event exposure. Major reasons individuals met DSM‐IV criteria, but not DSM‐5 criteria were the exclusion of nonaccidental, nonviolent deaths from Criterion A, and the new requirement of at least 1 active avoidance symptom. 標題：使用DSM‐Ⅳ和DSM‐5準則去估算全國的創傷經歷和PTSD患病率 撮要 : 透過網上小組集合美國全國成人樣本(N=2,953), 套用美國精神學協會的精神疾病診斷和統計手冊(DSM)的DSM‐5和DSM IV版本來診斷PTSD的患病率並比較。評估是在網上利用一個高度結構自我評估調查：創傷經歷，PTSD症狀，和功能障礙。創傷經歷若使用DSM‐5準則會有高比率(89.7%)，但標準是多重創傷經歷。利用同一事件(即所有症狀準則符合同一事件類別)和綜合事件(即症狀準則符合事件類別的混合)定義來決定PTSD病例。使用DSM‐5和同一事件定義的終身、過去12個月及過去6個月PTSD患病率分別為8.3%，4.7%和3.8%。所有6個DSM‐5患病率估量都比DSM‐IV者為低，雖然其中只有2個的差別是統計上有效的。DSM‐5 PTSD患病率是女性高於男性，而且隨着更大創傷經歷而增加。有些人符合DSM‐IV但不合DSM‐5診斷的主因是：撇除在準則A內非意外非暴力死亡和新加的最少一個主動迴避症狀的要求。 标题：使用DSM‐Ⅳ和DSM‐5准则去估算全国的创伤经历和PTSD患病率 撮要 : 透过网上小组集合美国全国成人样本(N=2,953), 套用美国精神学协会的精神疾病诊断和统计手册(DSM)的DSM‐5和DSM IV版本来诊断PTSD的患病率并比较。评估是在网上利用一个高度结构自我评估调查：创伤经历，PTSD症状，和功能障碍。创伤经历若使用DSM‐5准则会有高比率(89.7%)，但标准是多重创伤经历。利用同一事件(即所有症状准则符合同一事件类别)和综合事件(即症状准则符合事件类别的混合)定义来决定PTSD病例。使用DSM‐5和同一事件定义的终身、过去12个月及过去6个月PTSD患病率分别为8.3%，4.7%和3.8%。所有6个DSM‐5患病率估量都比DSM‐IV者为低，虽然其中只有2个的差别是统计上有效的。DSM‐5 PTSD患病率是女性高于男性，而且随着更大创伤经历而增加。有些人符合DSM‐IV但不合DSM‐5诊断的主因是：撇除在准则A内非意外非暴力死亡和新加的最少一个主动回避症状的要求。