A randomised controlled trial of epidural compared with non-epidural analgesia in labour

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Abstract

Objectives To investigate possible short and long term side effects of epidural analgesia, compared with non-epidural analgesia for pain relief in labour.

Design Randomised controlled study, with long term follow up by questionnaire. Analysis by intention-to-treat.

Setting Busy maternity unit within a district general hospital in England.

Participants Three hundred and sixty nine primigravid women in labour were included (randomised allocation: epidural n=184, non-epidural n=185).

Main outcome measures Backache at three and twelve months after delivery, instrumental delivery rates and maternal opinion of pain relief in labour.

Results No significant differences were found in the reported incidence of backache between the groups at three months: middle backache [22% vs 20%, χ2= 0.057, P=0.81; odds ratio (95% CI) 1.4(0.9-2.3)]; low backache [35% vs 34%, χ2= 0.009, P=0.92; odds ratio (95% CI) 1.0(0.6-1.6)]. Nor were there significant differences at 12 months: [middle backache 16% vs 16%, χ2= 0.013, P=0.91; odds ratio (95% CI) 1.0(0.5-1.8)]; or low backache [35% vs 27%, χ2= 1.91, P=0.17; odds ratio (95% CI) 1.4(0.9-2.3)]. The incidence of instrumental delivery was somewhat higher in the epidural group [30% vs 19%, odds ratio (95% CI) 1.77 (1.09-2.86)]. Maternal satisfaction was not significantly different between the groups.

Conclusions This study provided no evidence to support the suggestion of a direct association between the use of epidural anaesthesia in labour and the incidence of long term backache. Despite a significant proportion of women in each group not receiving their allocated analgesia, a significant difference in terms of instrumental delivery rates remained. Satisfaction in both groups of women was high.

Introduction

Pain relief for labour is an important concern for women both during pregnancy and in childbirth. The use of epidural analgesia in labour is widespread, with approximately 100,000 women in Britain using this form of pain relief each year1. The benefits of epidural analgesia in terms of pain relief are well recognised. However, discussions about possible effects of epidural analgesia on the progress of labour, and maternal, fetal and neonatal side effects2, 3, 4 have been hampered by lack of objective evidence5.

Analyses of observational data have suggested that epidural block may increase the incidence of chronic backache, chronic headache, bladder problems, tingling and numbness, and sensory confusion6. MacArthur and co-workers3 found that epidural analgesia during labour was associated with, but not necessarily causally related to, important and unrecognised long term morbidity. Questionnaires returned by 11,701 of the 30,096 women who had given birth in Birmingham between 1978 and 19853 revealed that 18.9% of women receiving epidural analgesia during labour reported new backache which began within three months of delivery and which persisted for more than six weeks, compared with only 10.5% of the women who had received alternative forms of pain relief. Another retrospective study found a difference of 17.8% and 11.7% between epidural and non-epidural groups7. Subsequent observational studies were unable to reproduce this work8, 9, 10.

If the association between epidural block and chronic backache were causal, the implications would be that, every year, tens of thousands of new mothers would suffer chronic backache as a result of choosing epidural analgesia in labour. In anticipation of potential legal complaints, it has become common practice for some anaesthetists to warn women requesting epidural analgesia for labour about the possible increased risk of backache.

Against this background it was felt there was a need for a controlled trial, in which standard policies of providing epidural or non-epidural analgesia were randomly compared, to establish whether there was a causal relationship between epidural analgesia in labour and long term backache5. It was hoped this would provide better information for both mothers and anaesthetists.

Section snippets

Methods

We compared epidural analgesia with non-epidural analgesia in spontaneously labouring primigravid women at term, with a normal obstetric and medical history and where there was no contraindication to either form of analgesia, and where written informed consent had been given. Only primigravid women were included so that reported problems might more easily be attributed to the index pregnancy. Primigravid women are also the ones who most frequently avail themselves of epidural analgesia.

Results

From Fig. 1 it can be seen that 31% (875/2840) of those counselled agreed to participate in the study. Of those who had agreed in antenatal clinic 42% (369/875) were randomised. There were many reasons for these drop-outs prior to randomisation including:

  • Women changing their minds between antenatal clinic and labour (60%).

  • Changing obstetric situation (20%).

  • Did not require analgesia (10%).

  • Other reasons (including anaesthetist not immediately available to site epidural if allocated, baby

Discussion

Previous to the planning of this study, the largest randomised study comparing pethidine and epidural analgesia for labour comprised 200 women11. No previous randomised study would have had sufficient power to detect small but clinically significant differences in some outcomes (e.g. rates of caesarean section), although subsequent larger studies have addressed this problem12, 13. No previous randomised study has examined the questions about epidural-related backache.

Prior to commencement,

Conclusion

Despite assertions to the contrary we have shown that it is possible to carry out a randomised controlled trial even in a complex situation highly affected by patient choice. Epidural analgesia and non-epidural analgesia, when analysed on an intention-to-treat basis, have similar outcomes in terms of reported postnatal backache. However, our study was not large enough to rule out small but clinically significant differences. Further follow up should include objective measurements of backache

Acknowledgements

The authors would like to thank the participating women and staff at the Maternity Department, North Staffordshire Hospital (NHS) Trust. The authors would also like to thank Dr C. MacArthur for the use of the questionnaire. The study was funded by WellBeing, and Ms P. Upton was supported by a grant from the North Staffordshire Medical Institute. The clinical trials work of Mr Richard Johanson and Ms Linda Lucking is supported by a grant from the NHS(E) West Midlands Research and Development

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