A total of 201 participants (151F/50M) were enrolled from June 2012 to December 2016. All patients who elected to undergo AT between June 2012 and December 2016 in the five clinics represented by the investigators were included in this registry/observational study. Mean age at the time of starting the therapy was 46.1 ± 10.9 years (range 19–74 years). Baseline BMI was 43.6 ± 7.4 kg/m2 (range 35–74 kg/m2). As of March 31, 2017, 173, 114, 42, and 30 participants started AT therapy at least 1, 2, 3, and 4 years ago, respectively. Because of withdrawals or lost to follow-up, weight measurements were taken for only 155, 82, 24, and 12 participants at years 1, 2, 3, and 4, respectively (see the participant disposition chart, Fig. 2). In this study, lost to follow-up participants are participants who were overdue for their most recent annual visit as of March 31, 2017, typically < 3 months overdue. From our experience, most lost to follow-up participants will return to the clinic to continue AT and obtain a new connector. Participants which discontinue AT and request A-Tube removal are considered withdrawn.
Weight Loss
For the modified intent to treat (mITT) population (excluding two participants with aborted gastrostomies and three participants who withdrew from the study prior to the gastrostomy), using a last observation carry-forward (LOCF) imputation for the18 participants who either withdrew from the therapy or were lost to follow-up, mean total weight loss (%TWL) (n = 173) at 1 year was 17.1% ± 9.6%. For the per-protocol population (n = 155), mean %TWL at 1 year was 18.2% ± 9.4%. Table 1 summarizes 1-year weight loss data and includes percent excess weight loss (%EWL) and absolute weight loss (AWL [kg]). At 1 year, of the mITT and per-protocol populations, 75 and 81%, respectively, achieved a minimum of 10% TWL, and 74 and 77%, respectively, achieved a minimum of 25% EWL.
Table 1 Mean 1-year weight loss results, with standard deviation and 95% confidence intervals, for modified intent to treat (mITT) and per-protocol populations. %total weight loss [%TWL], % excess weight loss [%EWL], and absolute weight loss [AWL] in kilograms Weight Loss Durability
Mean %EWL, %TWL, and AWL for participants who completed 1, 2, 3, and 4 years of therapy are presented in Table 2. So, as to not conflate durability of weight loss results with weight loss associated with different participant populations, we also examined weight loss for each completed year for all participants who completed 1, 2, 3, and 4 years of therapy (Suppl. Table. S1). As can be seen from the table and figure, first-year weight loss is maintained through at least the end of the fourth year. Weight loss (%TWL) in older participants (≥ 55 years) versus that of younger participants (< 55 years) (Suppl. Figure S2) and in participants with higher BMIs (≥ 50 kg/m2) versus lower BMIs (< 50 kg/m2) (Suppl. Figure S3) was investigated. Older and higher BMI participants trended towards greater weight loss (%TWL) than their younger and lower BMI counterparts, respectively, but the difference was not statistically significant.
Table 2 Mean weight loss, with standard deviation and 95% confidence intervals (CI), for year 1 through year 4 completers. percent total weight loss (%TWL), mean percent excess weight loss (%EWL), and mean absolute weight loss for years 1–4 Cardiometabolic Improvement
Although all sites monitored electrolytes, only two study sites monitored cardiometabolic status (blood pressure, lipids, glucose, glycated hemoglobin [HbA1C]); hence cardiometabolic data is only available from two sites.
With the exception of total cholesterol, clinically significant improvement in 1-year cardiometabolic data from baseline was observed. [HbA1C dropped 0.39% (p < 0.0001) from a 5.9% baseline; fasting glucose dropped 7.9 mg/dl (p < 0.01) from a 110 mg/dl baseline; systolic blood pressure dropped 12.1 mmHg (p < 0.0001) from a 141 mmHg baseline; diastolic blood pressure dropped 6.0 mmHg (p < 0.001) from a baseline of 88 mmHg; triglycerides dropped 25.5 mg/dl (p < 0.001) from a baseline of 133 mg/dl, and total cholesterol increased 4.3 mg/dl (p < 0.01) from a baseline of 186 mg/dl] (Table 3). For participants with diabetes, a 1.0% (p < 0.0001) mean reduction in 1-year HbA1C from 7.8% at baseline to 6.8% was observed.
Table 3 Mean cardiometabolic parameters at baseline and at 52 weeks and change at 1 year over baseline. glycated hemoglobin (HbA1C), glucose, blood pressure (BP), total cholesterol (CHO), and triglycerides, and glycated hemoglobin (HbA1C) for participants with diabetes only. Also shown is the change at 1-year from baseline, the 95% confidence intervals for the change from baseline, and the P value Complications
Table 4 lists all complications reported through March 31, 2017. In the periprocedural period (≤ 7 days post-gastrostomy), there was one serious complication, a case of peritonitis (without abscess), resolved with a 2-day course of intravenous antibiotics. Additionally, eight participants were hospitalized for benign pneumoperitoneum (likely, the result of insufflation) for observation and analgesic administration. In the post-procedural period (> 7 days post-gastrostomy), seven participants experienced a serious complication: all buried bumpers (two participants with two events each, seven patents with one event). The buried bumpers were treated by removal of the A-Tube, temporary replacement with a 20-French PEG tube, and subsequent replacement with an A-Tube. Although buried bumpers are a known complication of PEG tubes and are understood to be caused by excessive tension on the internal bumper against the gastric wall, it is not known what caused the excessive tension. The buried bumpers all occurred in the same clinic. The only complications that were not known complications of PEG tubes were three events (4% of all complications) of A-Tube rotation (e.g., where the internal end rotated from the fundus towards the pylorus) that occurred in two participants and treated by replacement of the A-Tube. Except for the complications discussed previously (peritonitis, buried bumpers, and A-Tube rotation), all other complications resolved spontaneously or with conservative therapies (oral analgesics, topical administrations, or oral antibiotics).
Table 4 Complications occurring in the periprocedural period (≤ 7 days from gastrostomy) and post-procedural period (> 7 days from gastrostomy) Persistent Fistulas Post A-Tube Removal
Of the 47 A-Tubes that have been removed, there were four incidents of persistent fistulas (e.g., the fistula not spontaneously closing) after A-Tube removal, one each occurring in the 13th, 25th, 34th, and 42nd month post-gastrostomy. Two were treated with argon plasma coagulation (APC) and proton pump inhibitors (PPIs) and closed successfully on the first re-attempt; the third and fourth did not respond to the APC/PPI regimen but closed successfully on the second re-attempt, utilizing endoscopic clips. As there were more A-Tubes removed in the first and second years (35 total) versus the third and fourth year (12 total), the data suggests that the rate of persistent fistulas increases significantly after 2 years post-gastrostomy (Suppl. Table S3).
A-Tube Replacement
Seven (7) A-Tubes reached, or were close to reaching, the end of their useful lives, and required replacement. Applying a Kaplan-Meier survival analysis on the A-Tube failure data, about 60% of participants at 4 years would have their original A-Tube (Suppl. Figure S2). We do not list A-Tube replacement in this report as a complication unless it occurred within 12 months of placement because it is understood that the A-Tubes have a finite lifetime.
The failed A-Tubes (Suppl. Figure S3) typically either were pitted or developed a bulge in the ~ 1-cm-length extra-fistular region between the skin and the Skin-Port. In three cases, the A-Tube developed either a leak or a tear in this same region, and in the other four cases, they were removed prior to a failure. The failure analysis by the manufacturer, Aspire Bariatrics, was a fungal (Candida) in-growth on ~ 1-cm extra-fistula segment, starting from the inside lumen and spreading outwards. Similar bulging was observed in another four A-Tubes, but as the A-Tube needed to be shortened (to accommodate the patient’s weight loss), the problematic section was removed and hence, the A-Tube did not need to be replaced.
Procedural Success
A total of 202 endoscopies to place the A-Tube were attempted on 201 participants, in aggregate, resulting in 199 successful A-Tube placements. In one participant, the gastrostomy was aborted due to inadequate transillumination. From a subsequent CT scan of the participant’s gastrointestinal tract, the endoscopist noted an unusual orientation of the participant’s stomach, decided to attempt another gastrostomy, was able to achieve adequate transillumination on the second attempt, and proceeded with a successful gastrostomy. In the second and third participants, the gastrostomy was aborted due to discovery of gastric varices in one case, and the liver blocking safe access to the stomach in the other case.
Discontinuation of Therapy
As of December 31, 2016, 155, 82, 24, and 12 participants completed 1, 2, 3, and 4 years of therapy, respectively. Of the 199 successful gastrostomies, 47 participants discontinued aspiration therapy and had their gastrostomy tubes removed; 17, 18, 9, 2, and 1 participants in the first, second, third, fourth, and fifth year, respectively. Approximately 1/3rd of the 47 “discontinued participants” experienced considerably less weight loss (%TWL) than the mean weight loss of their peers, while 2/3rd of such participants experienced approximately the same or greater weight loss than the mean weight loss of their peers (Suppl. Figure S4). Reasons cited by participants for discontinuation of the therapy include (i) achievement of goal weight (n = 13), (ii) inability or unwillingness to adhere to therapy (n = 9), (iii) fatigue with the therapy (n = 7), (iv) discomfort with the device (n = 7), (v) the decision to pursue bariatric surgery (n = 5), (vi) unrelated health issues (n = 3), (vii) personal economic issues (n = 1), (viii) incompatibility with work schedule (n = 1), and (ix) unknown (n = 1). It should be noted that the five participants who chose to undergo bariatric surgery did so successfully. Applying a Kaplan-Meier “survival” analysis (Suppl. Figure S5) to the withdrawal data, 91, 76, 64, and 53% of the participants who started aspiration therapy persisted with the therapy for 1, 2, 3, and 4 years, respectively.