This review was conducted with the aim of exploring the effect of preoperative smoking cessation on the risk of postoperative complications, and to identify the period of cessation needed to have a beneficial effect on improving surgical outcome.
The methodological quality of studies was often limited with essential information on follow‐up duration, period of smoking cessation, the control of confounding factors and the outcome assessor being blind to exposure status often missing. Only three studies validated smoking cessation status and therefore some patients may have reported being abstinent from smoking but may have been smoking, as revealed by one study that did validate smoking cessation status.17
There were also significant differences between the sample characteristics and medical procedures in the groups of current smokers, past smokers and non‐smokers which may limit the comparisons that can be made between the groups. For example, some aspects of surgical procedures such as wedge resections in thoracotomy surgery were more common in current smokers than past or non‐smokers.30
However, it is important that patients receive the medical care most suitable for their individual needs and therefore this would be difficult to control.
The studies included in the review encompassed a wide range of surgical procedures, which is both a benefit in terms of the generalisability of the findings but also increases the difficulty in comparing results from studies and interpreting the findings. Myles et al39
also highlighted that patients with more severe illness are more likely to reduce their consumption or stop smoking, which may influence the incidence of postoperative complications in past smokers from these studies. One study did not report the findings of patients who continued to smoke making comparisons more difficult.38
Two studies did not provide data on the risk of complications in patients who stopped smoking preoperatively,17,37
limiting the contribution of these studies to this review, and one study38
did not provide data on current smokers making comparisons between studies difficult.
There is the possibility that publication bias may affect the results of this review, although it is postulated that due to the nature of the research, negative findings on the effect of smoking cessation may be perceived to be as important as positive findings. The evidence elicited from this review was limited by the lack of studies in this area. For example, only one study explored the effects of smoking cessation on sputum volume. This is important, as sputum volume often increases after a short period of smoking abstinence, with smokers less able to clear the sputum after surgery. Sputum has been linked to an increase in pulmonary complications after surgery and therefore this may have important implications for recommendations on the most beneficial period of smoking cessation for patients undergoing surgery.41
Further research is urgently needed to assess the effect of preoperative smoking cessation on sputum volume and its implications for clinical practice.
Despite these limitations, some common elements of the effects of smoking cessation on postoperative complications became evident. It is widely documented that stopping smoking before surgery has substantial health benefits in the longer term and should be recommended to every smoker in order for them to gain maximum benefit from their treatment. As expected, patients who continued to smoke before surgery did have a higher rate of postoperative complications than non‐smokers. However, it also became evident that only one of the 12 studies found a significant increase in postoperative complications from short‐term preoperative smoking cessation. In addition, five studies also revealed that the risk or incidence of postoperative complications was significantly lower in past smokers than current smokers or that there was no significant difference between past smokers and non‐smokers. As only two studies specified the exact period of preoperative smoking cessation, identification of the optimal period of preoperative smoking cessation on postoperative complications could not be determined, although there did appear to be a trend towards reduced risk the longer the period of preoperative smoking cessation. It should also be considered that even a period of temporary short‐term abstinence before surgery may also increase patients' confidence in their ability to quit smoking and may lead to a longer term quit attempt in the future. There does also appear to be a benefit from even postoperative smoking cessation on longer‐term health outcomes in patients who have undergone a surgical procedure, although the methodological quality of the studies included in this review limits these findings.
Research providing clear definitions of the period of smoking cessation particularly within a few weeks of surgery is required, as only two studies with clear criteria were elicited by this review. If there are benefits to be gained from short‐term abstinence, the role of passive smoking on surgical complications also needs to be investigated to inform patients exposed to high levels of cigarette smoke.
What this paper adds
The effect of smoking on the risk of postoperative complications has been well documented; however, the effect of stopping smoking before surgery remains unclear. There is currently high variability in the smoking cessation advice offered by consultants and anaesthetists to patients scheduled for surgery.
This systematic review explored the findings from 12 prospective cohort studies. It was revealed that short‐term preoperative smoking cessation before surgery may reduce the risk of postoperative complications, although longer periods of cessation may provide the greatest health benefits. These findings have important implications for the advice given to smokers scheduled for surgery.
From the evidence included in this review across surgical specialties, it appears that patients who undertake a period of short‐term preoperative smoking cessation may reduce their risk of postoperative complications in comparison to patients who continue to smoke. There may be greater benefits to be gained from longer periods of preoperative smoking cessation, although shorter‐term cessation should not be discouraged. A risk benefit analysis may need to be completed for patients at a high risk from a potential increase in complications, such as increased sputum volume.