Interventions for Hiccups in Adults: A Scoping Review of Western and Eastern Approaches

Hiccups are caused by involuntary spasms of the diaphragm and external intercostal muscles. When persistent, they can significantly reduce the quality of life. However, comprehensive reviews of available treatments and their corresponding evaluation metrics remain scarce. This scoping review aimed to comprehensively map the interventions used to treat hiccups in adults and clarify the current state of outcome measures employed in existing research. We conducted a scoping review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) -ScR guidelines and the framework of Arksey and O'Malley. Using PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Ichushi-web databases, we identified studies published up to June 3, 2024. The search terms included "HICCUP," "HICCOUGH," and "SINGULTUS." A total of 3248 articles were identified, with 499 duplicates removed. After screening 2749 titles and abstracts, 2708 articles were excluded. Full-text reviews of 41 articles led to the exclusion of 18, resulting in 23 that met the inclusion criteria. Of these, 17 studies focused on pharmacological interventions, including baclofen, metoclopramide, methylprednisolone, and Shitei-to, while 6 studies examined nonpharmacological interventions, such as acupuncture, infrared therapy, rebreathing techniques, and cervical epidural block. Outcome measures were categorized into objective and subjective evaluations. Objective measures included complete cessation, partial cessation, frequency reduction, and time to complete cessation. Subjective measures assessed the distress caused by hiccups using patient-reported scales, such as the numerical rating scale. This scoping review identified 23 studies on hiccup interventions, including five randomized controlled trials on pharmacological agents and one study on a nonpharmacological approach. Studies included both Western and Eastern medicine, offering new perspectives on hiccup management. The outcome measures were primarily objective, with some patient-reported assessments. These findings provide a foundation for future research on hiccup treatment and evaluation methods.