Background

Nutritional deficiencies, such as iron and vitamin B12 deficiencies, are potential adverse consequences of bariatric surgery. Long-term data on anaemia after bariatric surgery are largely lacking. We aimed to investigate the risk of anaemia, iron and vitamin B12 deficiency anaemia, and vitamin B12 deficiency over 20 years in individuals who had bariatric surgery or received usual obesity care.

Methods

The prospective, controlled Swedish Obese Subjects study recruited people with obesity via recruitment campaigns in the mass media and at primary health-care centres, and was done at 480 primary health-care centres and in 25 surgical departments in Sweden. Eligible participants were aged 37–60 years and had a BMI of either 34 kg/m² or more (for men) or 38 kg/m² or more (for women). Participants were excluded if they had undergone previous bariatric surgery or had contraindicating conditions. Two main groups were formed: those who chose bariatric surgery, the type of which was determined by the operating surgeon, and a contemporaneously matched control group, created by use of 18 matching variables, who received usual non-surgical obesity care that ranged from lifestyle advice to no treatment. Haemoglobin concentration was measured during examination visits at baseline and at 1 year, 2 years, 3 years, 4 years, 6 years, 8 years, 10 years, 15 years, and 20 years of follow-up. Anaemia was defined as a haemoglobin concentration of less than 120 g/L for women and 130 g/L for men. The primary, non-specified outcome was the incidence of anaemia, and was assessed in the as-treated population, which comprised only patients who received the actual treatment. The associations between treatment type and anaemia are expressed as unadjusted hazard ratios (HRs) and HRs adjusted for age, sex, BMI, menopausal status, education, diabetes, and hypertension, with 95% CIs. This study is registered in ClinicalTrials.gov, NCT01479452, and is closed to new participants, with follow-up ongoing.

Findings

Between Sept 1, 1987, and Jan 31, 2001, 6905 individuals were assessed for eligibility, of whom 5335 were eligible. Of these, we included 2007 patients who chose bariatric surgery (266 in the gastric bypass group, 1365 in the vertical-banded gastroplasty group, and 376 in the gastric banding group) and 2040 matched controls who received usual obesity care. During a maximum of 20 years and a median of 10 years (IQR 3–20) of follow-up, there were 133 anaemia events in the gastric bypass group, 359 in the vertical-banded gastroplasty group, 101 in the gastric banding group, and 261 in the control group. Compared with the control group (13 cases per 1000 person-years, 95% CI 11–14), the incidence of anaemia was higher in the gastric bypass group (64 cases per 1000 person-years, 53–74; HR 5·05, 95% CI 3·94–6·48; p<0·0001), the vertical-banded gastroplasty group (23 cases per 1000 person-years, 21–26; 2·67, 2·25–3·18; p<0·0001), and the gastric banding group (26 per 1000 person-years, 21–31; 2·76, 2·15–3·52; p<0·0001). These associations remained after adjustment.

Interpretation

Our findings highlight the increased risk of anaemia after bariatric surgery and the importance of long-term compliance to nutritional supplementation and monitoring to enable prevention and early detection of serious nutritional deficiencies after bariatric surgery.

Funding

Swedish Research Council, the Swedish state under the agreement between the Swedish Government and the county councils, the Swedish Diabetes Foundation, the Swedish Heart-Lung Foundation, and the Novo Nordisk Foundation.

中文翻译：

---

减肥手术后贫血的长期风险：瑞典肥胖受试者研究的结果

背景

营养缺乏，如铁和维生素 B12 缺乏，是减肥手术的潜在不良后果。很大程度上缺乏减肥手术后贫血的长期数据。我们旨在调查接受减肥手术或接受常规肥胖治疗的个人在 20 年内发生贫血、铁和维生素 B12 缺乏症以及维生素 B12 缺乏症的风险。

方法

这项前瞻性、受控的瑞典肥胖受试者研究通过大众媒体和初级卫生保健中心的招聘活动招募了肥胖患者，并在瑞典的 480 个初级卫生保健中心和 25 个外科部门进行。符合条件的参与者年龄在 37-60 岁之间，BMI 为 34 kg/m ²或更高（男性）或 38 kg/m ²或更多（女性）。如果参与者之前接受过减肥手术或有禁忌症，则被排除在外。形成了两个主要组：选择减肥手术的人，手术类型由手术外科医生决定，以及同期匹配的对照组，使用 18 个匹配变量创建，他们接受常规的非手术肥胖护理，包括生活方式建议不要治疗。血红蛋白浓度是在基线和 1 年、2 年、3 年、4 年、6 年、8 年、10 年、15 年和 20 年随访期间的检查访问期间测量的。贫血定义为女性血红蛋白浓度低于 120 g/L，男性低于 130 g/L。主要的、未指定的结果是贫血的发生率，并在接受治疗的人群中进行评估，其中仅包括接受实际治疗的患者。治疗类型与贫血之间的关联表示为未调整的风险比 (HR) 和针对年龄、性别、BMI、更年期状态、教育程度、糖尿​​病和高血压调整的 HR，具有 95% 的 CI。该研究已在 ClinicalTrials.gov 注册，NCT01479452，不对新参与者开放，后续正在进行中。

发现

1987 年 9 月 1 日至 2001 年 1 月 31 日期间，6905 人接受了资格评估，其中 5335 人符合资格。其中，我们纳入了 2007 名选择减肥手术的患者（胃绕道组 266 名、垂直带状胃成形术组 1365 名和胃束带组 376 名）和 2040 名接受常规肥胖治疗的匹配对照。在最长 20 年和中位 10 年（IQR 3-20）的随访期间，胃绕道组有 133 例贫血事件，垂直带胃成形术组有 359 例，胃束带组有 101 例，对照组261例。与对照组（13例/1000人年，95%CI 11-14）相比，胃绕道组贫血发生率更高（64例/1000人年，53-74；HR 5·05 , 95% CI 3·94–6·48; p<0·0001), 垂直带状胃成形术组（23 例/1000 人年，21-26；2·67，2·​​25-3·18；p<0·0001）和胃带组（26 例/1000 人年） , 21-31; 2·76, 2·15-3·52; p<0·0001)。这些关联在调整后仍然存在。

解释

我们的研究结果强调了减肥手术后贫血的风险增加，以及长期遵守营养补充和监测的重要性，以便预防和及早发现减肥手术后的严重营养缺乏。

资金

瑞典研究委员会，根据瑞典政府与郡议会之间的协议，瑞典国家、瑞典糖尿病基金会、瑞典心肺基金会和诺和诺德基金会。