Preoperative prediction of type 2 diabetes remission after Roux-en-Y gastric bypass surgery: a retrospective cohort study

Abstract

Background: About 60% of patients with type 2 diabetes achieve remission after Roux-en-Y gastric bypass (RYGB) surgery. No accurate method is available to preoperatively predict the probability of remission. Our goal was to develop a way to predict probability of diabetes remission after RYGB surgery on the basis of preoperative clinical criteria.

Methods: In a retrospective cohort study, we identified individuals with type 2 diabetes for whom electronic medical records were available from a primary cohort of 2300 patients who underwent RYGB surgery at the Geisinger Health System (Danville, PA, USA) between Jan 1, 2004, and Feb 15, 2011. Partial and complete remission were defined according to the American Diabetes Association criteria. We examined 259 clinical variables for our algorithm and used multiple logistic regression models to identify independent predictors of early remission (beginning within first 2 months after surgery and lasting at least 12 months) or late remission (beginning more than 2 months after surgery and lasting at least 12 months). We assessed a final Cox regression model with a consistent subset of variables that predicted remission, and used the resulting hazard ratios (HRs) to guide creation of a weighting system to produce a score (DiaRem) to predict probability of diabetes remission within 5 years. We assessed the validity of the DiaRem score with data from two additional cohorts.

Findings: Electronic medical records were available for 690 patients in the primary cohort, of whom 463 (63%) had achieved partial or complete remission. Four preoperative clinical variables were included in the final Cox regression model: insulin use, age, HbA1c concentration, and type of antidiabetic drugs. We developed a DiaRem score that ranges from 0 to 22, with the greatest weight given to insulin use before surgery (adding ten to the score; HR 5·90, 95% CI 4·41–7·90; p<0·0001). Kaplan-Meier analysis showed that 88% (95% CI 83–92%) of patients who scored 0–2, 64% (58–71%) of those who scored 3–7, 23% (13–33%) of those who scored 8–12, 11% (6–16%) of those who scored 13–17, and 2% (0–5%) of those who scored 18–22 achieved early remission (partial or complete). As in the primary cohort, the proportion of patients achieving remission in the replication cohorts was highest for the lowest scores, and lowest for the highest scores.

Interpretation: The DiaRem score is a novel preoperative method to predict the probability of remission of type 2 diabetes after RYGB surgery.

Funding: Geisinger Health System and the US National Institutes of Health.

Figure 1. Flow chart describing the patient selection strategy for the Primary cohort

The indicated sample sizes (N) were used for the corresponding type of analysis, before and after stratification by insulin use [i.e., overall remission (partial + complete), predictors of early or late (partial + complete) remission].

Figure 2. Kaplan-Meier survival estimates with 95% confidence intervals over five years showing the percent (%) number of patients with diabetes remission after RYGB surgery, stratified by pre-operative use of insulin

(A) Percent remission according to the definition of “partial + complete” remission of T2D. Patients that were not using insulin preoperatively had a probability range of 70·6%-90·1% for achieving remission of T2D (early or late). T2D patients using insulin preoperatively (T2D+I), on the other hand, had a probability range of 10·3%–31·1% for achieving remission of T2D (early or rate). (B) Percent remission according to the definition of “complete” remission of T2D. Patients that were not using insulin preoperatively had a probability range of 42·4%–77·7% for achieving remission of T2D (early or late). T2D patients using insulin preoperatively (T2D+I), on the other hand, had a probability range of 4·4%–15·4% for achieving remission of T2D (early or rate). More cohort information is provided in the Supplemental information section (Tables S1–S3).

Figure 3. Kaplan-Meier survival estimates with 95% confidence intervals (CIs) over five years showing the percent (%) probability for T2D remission after RYGB surgery, stratified by the DiaRem score

(A) According to the definitions of “partial + complete” diabetes remission, the lowest DiaRem score (i.e., the 0–2 grouping) predicted high probability for T2D remission (88%–99%), while, the highest DiaRem score (18–22) predicted low probability for going into T2D remission (2%). Intermediate DiaRem scores predicted intermediate probabilities for T2D remission. (B) According to the definition of “complete” diabetes remission, the lowest DiaRem score again predicted high probability for T2D remission (61%–94%), while, the highest DiaRem score predicted no remission (0%). Intermediate DiaRem scores predicted intermediate probabilities for remission. Each DiaRem score line is shown in black color and the corresponding CIs are shown in alternating dotted or dashed gray lines. More cohort information is provided in the Supplemental information section (Tables S6 & S7).

Figure 4. DiaRem scores predicting percent (partial + complete) T2D remission in three independent cohorts, 14 months after RYGB surgery

Primary: the main cohort from central Pennsylvania that was used to develop the DiaRem score. AZ: the first replication cohort from Scottsdale, Arizona. PA: the second replication cohort also from Central Pennsylvania. Cochran-Armitage trend tests were used to confirm that lower DiaRem scores were associated with higher chance of remission in each cohort (P < 0·0001). When pooling together the DiaRem scores from the three cohorts, the following mean probability ranges were obtained: DiaRem 0–2: 87%, 3–7: 66%, 8–12: 32%, 13–17: 16%, 18–22: 5%. Basic characteristics of the three cohorts are provided in Table 1.