We read with great interest, the systematic review by Katzka and Castell of the efficacy and adverse effects of pneumatic dilation for achalasia.1 Katzka and Castell reviewed 26 studies, 18 of which were performed with a Rigiflex balloon, which is currently used in most centres. The pooled results showed an 88% 1-year efficacy, and a perforation rate of 2% with this type of balloon, gradually declining with time. Efficacy and durability of success were increased by applying repeated dilations during the first treatment, but this came at the expense of an increased perforation rate (4%). Although not assessed in this meta-analysis, recurrent symptoms can be managed by re-dilation in the majority of patients, leading to long-term symptom control, as a number of studies have shown.2, 3 Two important findings partially explain the variability of the efficacy and complication rates of pneumatic dilation amongst individual studies: first, the use of different and nonstandardised outcome measures and second, the use of a multitude of dilation protocols, both of which compromise comparability and meta-analysis of the available studies. Only 6 of the 29 studies analysed the symptomatic outcome using standardised questionnaires, i.e. the Eckardt or Vantrappen scores.4, 5 A fair correlation exists between both scores, both before and after treatment,6 but one advantage of the Eckardt score for assessing the symptomatic outcome in future trials is its wider score range, which may yield increased sensitivity to change. The recent large-scale multi-centre European trial used the Eckardt score as a principal outcome measure.7 As the efficacy of pneumatic dilation is now well-established, future studies should be designed to select an optimal protocol that can be used in subsequent trials comparing dilation to other approaches, including surgical and minimally invasive treatments. On the basis of the presented data and the recent multi-centre European trial,7 which identified a clearly increased risk of perforation when starting with a 3.5 cm balloon, we feel that a graded multiple dilation protocol, starting with a 3 cm balloon diameter, should be endorsed as the standard treatment. When adopting this protocol, it is of paramount importance to maintain a high clinical index of suspicion for perforation, which can be managed conservatively in most patients.8 Whether the graded dilations should be performed on the same day, subsequent days or with longer intervals, remains a matter of debate and is worthy of investigation in future controlled trials. Taking into account the low prevalence of achalasia, these trials are likely to require multi-centre collaboration to compare the outcomes of randomised treatment protocol variants. The same trials may evaluate the gain of novel objective outcome measures, such as the timed barium oesophagogram, oesophageal muscle thickness on intraluminal ultrasound, or bolus movement assessed by intraluminal impedance monitoring. Finally, these outcome measures can also be evaluated for their ability to determine the optimal timing of retreatment when symptoms start to recur after an initial favourable response.2, 3 Declaration of personal and funding interests: None.