Carlsson Lena Ms, Peltonen Markku, Jacobson Peter, Andersson-Assarsson Johanna C, Svensson Per-Arne, Taube Magdalena, Karlsson Cecilia, Ahlin Sofie, Kristensson Felipe M, Perkins Rosie, Arnetorp Ida, Carlsson Alexander, Admeus Lucas, Langegård Elin, Carlsson Björn, Sjöholm Kajsa
Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Finnish Institute for Health and Welfare, Helsinki, Finland.
Eur J Epidemiol. 2025 May 12. doi: 10.1007/s10654-025-01237-6.
Some studies of obesity treatments use control groups identified from real-world registers, which may differ from people with obesity in the general population. We evaluated whether such control groups affect the results. The SOS study examines long-term mortality post-bariatric surgery. Among volunteers with obesity, 2,007 individuals underwent surgery, while a control group of 2,040 individuals was matched using 18 variables. Age was 37-60 years and BMI was ≥ 34/≥38 kg/m for men and women, respectively. We subdivided the control group into those with an obesity diagnosis (n = 177) and those without an obesity diagnosis (n = 1,863) in the Swedish National Patient Register prior to study inclusion. Mortality was determined over a median follow-up period of 26 years. The controls with a prior obesity diagnosis had a higher mortality rate than the controls without a prior obesity diagnosis, with 19.7 (95% CI, 15.5-25.1) and 14.4 (95% CI, 13.3-15.7) deaths per 1000 person-years, respectively. This corresponds to a hazard ratio of 1.45 (95% CI, 1.12-1.89; p = 0.005) and a 3.4-year shorter life expectancy. These results were confirmed in another cohort (n = 2,759, HR = 1.82 [95% CI, 1.47-2.25; p<0.001] and a 6.1-year shorter life expectancy). Controls with obesity identified from real-world datasets may be in poorer health than those who voluntarily participate in clinical studies. Consequently, selection bias could lead to an overestimation of the survival benefits of obesity treatments in research using controls identified by prior obesity diagnosis.
一些肥胖治疗研究使用从真实世界登记处确定的对照组，这些对照组可能与一般人群中的肥胖者有所不同。我们评估了这样的对照组是否会影响研究结果。SOS研究考察了减肥手术后的长期死亡率。在肥胖志愿者中，2007人接受了手术，同时使用18个变量匹配了一个由2040人组成的对照组。年龄在37至60岁之间，男性和女性的BMI分别≥34/≥38kg/m²。在纳入研究之前，我们将瑞典国家患者登记处的对照组细分为有肥胖诊断的（n = 177）和没有肥胖诊断的（n = 1863）。在中位随访期26年期间确定死亡率。有肥胖诊断史的对照组的死亡率高于无肥胖诊断史的对照组，每1000人年的死亡人数分别为19.7（95%CI，15.5 - 25.1）和14.4（95%CI，13.3 - 15.7）。这相当于风险比为1.45（95%CI，1.12 - 1.89；p = 0.005），预期寿命缩短3.4年。这些结果在另一个队列中得到了证实（n = 2759，HR = 1.82 [95%CI，1.47 - 2.25；p<0.001]，预期寿命缩短6.1年）。从真实世界数据集中确定的肥胖对照组的健康状况可能比自愿参与临床研究的对照组更差。因此，在使用先前肥胖诊断确定的对照组进行的研究中，选择偏倚可能导致对肥胖治疗生存益处的高估。
