OBJECTIVETo determine the incidence and risk factors associated to with refractory constipation patients complicated with superior mesenteric artery syndrome (SMAS), and to observe the role of nutritional support in its treatment.

METHODSA prospective nested case-control study was conducted from a constipation cohort(n=973) to assess the incidence and risk factors of SMAS. Pitents with SMAS were matched to controls with a ratio of 1:4 by age and gender. Cases developed SMAS in long-term follow-up(n=26) and controls did not(n=104). Nutritional support was used in 26 patients with SMAS. The efficacy of nutritional support was evaluated by retrospective analysis.

RESULTSThe incidence of SMAS in this cohort of patients was 2.7%. Multivariate logistic analysis revealed BMI≤18 kg/m(2) (OR=2.89, 95%CI:1.14-7.31) and prolonged colon transit time(OR=3.57, 95%CI:1.36-9.35) were independent risk factors of SMAS in patients with refractory constipation. A total of 22 patients recovered after treatment of nutritional support. The successful rate of conservative treatment was 84.6%. The clinical symptoms, gastrointestinal quality of life index, Wexner constipation score and nutritional status were all significantly improved after treatment.

CONCLUSIONA BMI of less than 18 kg/m(2) and prolonged colon transit time are independent risk factors in refractory constipation patients complicated with SMAS. Nutrition support should be carried out according to illness condition and nutritional status, and combined with theatment of constipation simultaneously.