The esophageal pH study was first described in 1974 [42] and is considered the gold standard for the diagnosis of GERD. Three different patterns of reflux can be identified based on esophageal pH study: supine, upright, and bipositional. Although once thought that different patterns would have different surgical outcomes, [43] the most recent literature indicates an equivalent surgical result irrespective of these pH study patterns [44, 45].

Symptomatic patients with a positive pH study generally do better than patients with symptoms and a negative pH study [46]. The symptom association probability index (SAP), which associates reflux episodes with patient reported symptoms, is an important instrument for surgical patient selection, and is especially valuable in the selection of patients with atypical symptoms for surgical treatment [47, 29]. Unfortunately, only half of patients with abnormal esophageal acid exposure have a positive SAP [48]. In a well-controlled trial, patients with an abnormal pH study and typical symptoms were randomized according to the SAP. The surgical outcomes were similar between patients with positive and negative SAP when measured objectively and subjectively at 3 months and 5 years, as were the number of reoperations within 6 years (12.8 and 14 %, respectively) [49]. The same group reported that the response to surgery is similar in reflux proven patients (abnormal pH study) irrespective of the presence or absence of esophagitis [33]. Esophageal acid hypersensitivity is defined by a technically normal physiologic 24 h pH study and positive SAP correlation. Although caution must be exercised in this population, there are reports of good surgical results in patients with esophageal acid hypersensitivity [50]. The 48 h-wireless pH study and impedance pH study increase the sensitivity and SAP compared to traditional 24 h pH study. This can be of value in patients with initially negative 24 h pH study, and in patients with atypical symptoms [51–54]. Older methods such as the Bernstein test are rarely performed today.

After reviewing the main predictors of good surgical outcomes and consequently how to select patients for surgical treatment of GERD, the final decision is whether surgery or medical treatment would be best for the patient.

In 2011 two randomized trials published results comparing medical and surgical GERD treatment. Anvari et al. [55] demonstrated that at 3-year follow-up surgery provided better symptomatic control and quality of life than the PPI alone, but there was no difference in GERD symptom scale or pH study results. Treatment failures were similar in both groups, being 11.8 % for surgery and 16 % for medical therapy. The LOTUS trial reported that at 5 years patients who underwent surgery had better control of regurgitation, but similar heartburn control, and an increased frequency of dysphagia and gas bloat. Treatment failure, the main outcome of the report, occurred in 15 % of surgical patients and 6 % of PPI therapy patients, a statistically significant difference [56]. It is important to highlight that both studies included only patients with typical symptoms responsive to PPI prior to randomization, and the surgical technique and medical treatment were standardized.

A meta-analysis of four randomized trials reported before 2010, which included 1,232 patients, reported an improvement in quality of life at 1 year after surgery when compared to medical therapy. It also suggested that heartburn and regurgitation are better controlled by surgery, but persistent dysphagia is more common after surgical procedure. Unfortunately, these conclusions are only valid for short and medium term follow-up [57].

Cost effectiveness analysis has been applied to compare the results of medical and surgical therapy for GERD. Two reports, one from the REFLUX Trial Group and another for Anvari et al., suggested that surgery might be cost effective in the treatment of patients who need long-term control of GERD [58, 59], Figure 5.1 (graph from Anvari Study). Although both studies suggested that surgery is more cost effective, the results are dependent on which measure was used for the analysis, the cost of the PPI, and the long-term effectiveness of the surgical repair. The long-term results of surgical therapy are specifically discussed in the literature, and a recent report of 15-year follow-up of 86 patients after LARS and open fundoplication demonstrated that 76.7 % of patients were asymptomatic, with only 10.5 % of patients complaining of heartburn and regurgitation that affects their everyday life. Of those, nearly half had no objective evidence of GERD. Dysphagia was observed in 3.5 % of the series, with two cases related to previous strictures and one secondary to the fundoplication. Gas bloat was by far the most common adverse event, being reported in 43 % of the patients. In the laparoscopic group 91 % of the patients were satisfied with the surgical results. Fifteen percent (n = 13) of the patients were using PPI on a daily basis, but only six of them had objective endoscopic signs related to recurrent reflux [60].