CRD summary

The authors concluded that topical and injected local anaesthetic appeared to modestly and similarly reduce post-tonsillectomy pain; topical application may be safer and should be the method of choice. Limitations in review methods and limited evidence about topical anaesthetics suggest that the conclusions may not be reliable.

Authors' objectives

To evaluate the effects of perioperative local anaesthetic agents on post-tonsillectomy pain.

Searching

MEDLINE (from 1952), EMBASE (from 1974) and Cochrane Central Register of Controlled Trials (CENTRAL) were searched to 2008 for studies published in English. Search terms were reported

Study selection

Randomised controlled trials (RCTs) that evaluated either injection of local anaesthetic into the tonsillar region before/following tonsillectomy or topical local anaesthetic applied to the tonsillar fossa following tonsillectomy were eligible for inclusion. Studies could be in adults or children. Studies could use any surgical method of tonsillectomy, but had to use a standardised anaesthetic protocol. Studies that evaluated local anaesthetic applied as a topical spray and studies of patients who underwent tonsillectomy in combination with other procedures were excluded. Primary review outcomes were resting pain scores at four to six hours, 20 to 24 hours and five days postoperatively. Secondary outcomes were the amount of additional postoperative analgesia and adverse events.

All but two studies evaluated injection of local anaesthetic; two studies applied the local anaesthetic topically. Studies evaluated a variety of local anesthetic agents and concentrations; studies also varied in their use of concomitant epinephrine in treatment and control groups. About half of the studies included only children (age two to 17) and about half included only adults.

One reviewer identified potentially relevant studies and two reviewers independently selected studies.

Assessment of study quality

Validity was assessed using the following criteria described by Hollis et al: adequate randomisation; group size greater than 10; intention-to-treat analysis and less than 20% lost to follow-up; blinding of outcome assessor; and use of validated outcome assessment for pain. Studies were included in the review only if they met all criteria.

Two reviewers independently assessed validity and resolved differences by discussion.

Data extraction

Means and standard deviations were extracted. A single combined treatment effect size was calculated for studies with multiple local anaesthetic treatment arms. Time points closest to six and 24 hours were used where multiple time points were reported.

One author extracted data.

Methods of synthesis

Pooled standardised mean differences (SMD) and 95% confidence intervals (CI) were calculated using a fixed effect model. Heterogeneity was assessed using the Χ² and the I² statistics. Subgroup analysis was used to examine the influence of mode of application of anaesthetic (injection or topical), studies that did not randomise individual patients and studies that assessed outcomes using observation. Analyses were repeated after including potentially eligible studies that failed to meet all the validity criteria. Other differences between studies were discussed. Analysis was repeated including lower-quality studies.

Results of the review

Thirteen RCTs were included (n=777). In 11 studies individual patients were randomised; two studies randomised sides within patients.

Compared with placebo, local anaesthetic significantly reduced pain at four to six hours (SMD -0.66, 95% CI -0.82 to -0.50; 11 studies), pain at 20 to 24 hours (SMD -0.34, 95% CI -0.51 to -0.18; 11 studies) and at five days (SMD -0.97, 95% CI -1.30 to -0.63; three studies). Significant heterogeneity was found for all three analyses (I²=93%, 89% and 68%).

Both local injection and topical application significantly reduced pain over all time periods. Only one of two studies provided data about topical agents.

Most studies (seven out of 10) reported no difference in the need for additional analgesia; three studies reported use of significantly less supplemental analgesia in local anaesthetic groups.

Most studies that assessed adverse events reported no difference between treatment groups. One study reported significantly greater blood loss and secondary haemorrhage from the control side. One fatality was reported in a patient who received local infiltration, developed cervical osteomyelitis and died.

Authors' conclusions

Topical and injected local anaesthetic appeared to modestly and similarly reduce post-tonsillectomy pain. Topical application avoided the potential adverse effects of infiltration and should be the method of choice.

CRD commentary

The review question was clearly stated and appropriate inclusion criteria were defined. Several relevant sources were searched, but no attempts were made to minimise publication and language biases. Methods were used to minimise reviewer errors and bias in the assessment of validity, but similar methods were not used for study selection and data extraction. Only higher-quality RCTs were included in the main analyses. Studies were combined using meta-analysis, heterogeneity was assessed, various subgroup analyses were conducted and other potential causes of differences between studies were discussed. Evidence about the effects of topical anaesthetics was based on one or two studies (n=42 to 140) and was therefore limited. Limitations in the methods used to conduct this review and limited evidence about topical anaesthetics suggest that the conclusions may not be reliable.

Implications of the review for practice and research

Practice: The authors stated that topical anaesthetic applied using swabs appeared to provide a similar level of analgesia as injection without the potential adverse effects and should therefore be the method of choice.

Research: The authors stated that a multicentre RCT was required to provide additional evidence. Future studies should differentiate patients who underwent tonsillectomy and adenoidectomy, and use standardised anaesthetic and post-operative analgesic protocols and validated methods to assess outcomes.

Funding

Not stated.

Bibliographic details

Grainger J, Saravanappa N. Local anaesthetic for post-tonsillectomy pain: a systematic review and meta-analysis. Clinical Otolaryngology 2008; 33(5): 411-419. [PubMed: 18983373]

Original Paper URL

http://onlinelibrary.wiley.com/doi/10.1111/j.1749-4486.2008.01815.x/abstract

Indexing Status

Subject indexing assigned by NLM

MeSH

Adult; Anesthesia, Local; Child; Evidence-Based Medicine; Humans; Pain Measurement; Pain, Postoperative /drug therapy; Randomized Controlled Trials as Topic; Tonsillectomy

AccessionNumber

12009101270

Database entry date

13/01/2010

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.