Individual prediction of response to pneumatic dilation in patients with achalasia.

During nine years, 157 consecutive patients with achalasia have been dilated in our unit. First, the long-term effect of dilation on clinical status was evaluated. The probability of being in clinical remission eight years after first dilation was 51%. The pressure of the LES measured after dilation was highly predictive of the long-term clinical evolution. Second, a predictive model of the individual response to pneumatic dilation was developed and simplified. Therapy was effective in 80% of the patients, after one to four dilations. Younger age was the only factor significantly associated with ineffective therapy. Depending on the prognosis of the outcome calculated with the predictive model, patients were classified in groups of risk that showed a different rate of ineffective, therapy. In the simplified model, age < or = 20 years, male gender, esophageal body diameter < or = 3 cm, esophageal body basal pressure > 15 mm Hg, and pressure of the lower esophageal sphincter > 30 mm Hg were predictors of a poor response to dilation. We conclude that pneumatic dilation is an effective therapy for achalasia. A predictive model was useful to classify the patients in groups with a different risk for ineffective dilation. A simplification of this model could be used to predict the response to dilation.