Clinical characteristics of absent contractility and ineffective esophageal motility: a multicenter study in Japan.

BACKGROUND AND AIM: Absent contractility (AC) and ineffective esophageal motility (IEM) are esophageal hypomotility disorders diagnosed using high-resolution manometry (HRM). Patient characteristics and disease course of these conditions and differential diagnosis between AC and achalasia are yet to be elucidated. METHODS: A multicenter study involving 10 high-volume hospitals was conducted. Starlet HRM findings were compared between AC and achalasia. Patient characteristics including underlying disorders and disease courses were analyzed in AC and IEM. RESULTS: Fifty-three patients with AC and 92 with IEM were diagnosed, while achalasia was diagnosed in 1784 patients using the Chicago classification v3.0 (CCv3.0). The cut-off integrated relaxation pressure (IRP) value at 15.7 mmHg showed maximum sensitivity (0.80) and specificity (0.87) for differential diagnosis of AC from type I achalasia. While most ACs were based on systemic disorders such as scleroderma (34%) and neuromuscular diseases (8%), 23% were sporadic cases. The symptom severity of AC was not higher than that of IEM. Regarding the diagnosis of IEM, the more stringent CCv4.0 excluded 14.1% of IEM patients than the CCv3.0, although patient characteristics did not change. In patients with the hypomotile esophagus, concomitance of reflux esophagitis was associated with low distal contractile integral and IRP values. AC and IEM transferred between each other, paralleling with the underlying disease course, although no transition to achalasia was observed. CONCLUSION: A successful determination of the optimal cut-off IRP value was achieved using the starlet HRM system to differentiate AC and achalasia. Follow-up HRM is also useful for differentiating AC from achalasia. Symptom severity may depend on underlying diseases instead of hypomotility severity.