Background: Persistent and intractable hiccups (typically defined as lasting for more than 48 hours and one month respectively) can be of serious detriment to a patient's quality of life, although they are relatively uncommon. A wide range of pharmacological and non-pharmacological interventions have been used for the treatment of persistent and intractable hiccups. However, there is little evidence as to which interventions are effective or harmful.
Objectives: The objective of this review was to evaluate the effectiveness of pharmacological and non-pharmacological interventions used in the treatment of persistent and intractable hiccups of any aetiology in adults.
Search methods: Studies were identified from the following databases: CENTRAL, CDSR, DARE, MEDLINE, EMBASE, CINAHL, PsychINFO and SIGLE (last search March 2012). The search strategy for all the databases searched was based on the MEDLINE search strategy presented in Appendix 1. No additional handsearching of journals was undertaken. Investigators who are known to be carrying out research in this area were contacted for unpublished data or knowledge of the grey literature.
Selection criteria: Studies eligible for inclusion in this review were randomised controlled trials (RCTs) or controlled clinical trials (CCTs).
Inclusion criteria: adults (over 18 years old) diagnosed with persistent or intractable hiccups (hiccups lasting more than 48 hours), treated with any pharmacological or non-pharmacological intervention.
Exclusion criteria: less than ten participants; no assessment of change in hiccup frequency or intensity in outcome measures.
Data collection and analysis: Two independent review authors assessed each abstract and title for relevance. Disagreement on eligibility was resolved by discussion. Where no abstract was available the full paper was obtained and assessed. We obtained full copies of the studies which met the inclusion criteria for further assessment. Two review authors independently collected data from each appropriate study and entered them into the software Review Manager 5. Two independent review authors assessed the risk of bias using the RevMan 5 'Risk of bias' table following guidance from the Cochrane Handbook of Systematic Reviews of Interventions (Higgins 2009).
Main results: A total of four studies (305 participants) met the inclusion criteria. All of these studies sought to determine the effectiveness of different acupuncture techniques in the treatment of persistent and intractable hiccups. All four studies had a high risk of bias, did not compare the intervention with placebo, and failed to report side effects or adverse events for either the treatment or control groups. Due to methodological differences we were unable to perform a meta-analysis of the results. No studies investigating pharmacological interventions for persistent and intractable hiccups met the inclusion criteria.
Authors' conclusions: There is insufficient evidence to guide the treatment of persistent or intractable hiccups with either pharmacological or non-pharmacological interventions.The paucity of high quality studies indicate a need for randomised placebo-controlled trials of both pharmacological and non-pharmacological treatments. As the symptom is relatively rare, trials would need to be multi-centred and possibly multi-national.