Spontaneous pneumothorax

Abstract

Introduction

The incidence of spontaneous pneumothorax is 24/100,000 a year in men and 9.9/100,000 a year in women in England and Wales. The major contributing factor is smoking, which increases the likelihood by 22 times in men, and by 8 times in women. While death from spontaneous pneumothorax is rare, rates of recurrence are high, with one study of men in the USA finding a total recurrence rate of 35%.

Methods and outcomes

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments in people presenting with spontaneous pneumothorax? What are the effects of interventions to prevent recurrence in people with previous spontaneous pneumothorax? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

Results

We found 17 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

Conclusions

In this systematic review we present information relating to the effectiveness and safety of the following interventions: chest-tube drainage (alone or plus suction), chest tubes (small, standard sizes, one-way valves), needle aspiration, and pleurodesis.

Key Points

Spontaneous pneumothorax is defined as air entering the pleural space without any provoking factor, such as trauma, surgery, or diagnostic intervention.

• Incidence is 24/100,000 a year in men, and 10/100,000 a year in women in England and Wales, and the major contributing factor is smoking, which increases the likelihood by 22 times in men and by 8 times in women.

• While death from spontaneous pneumothorax is rare, rates of recurrence are high, with one study of men in the US finding a total recurrence rate of 35%.

Overall, we found insufficient RCT evidence to determine whether any intervention is more effective than no intervention for spontaneous pneumothorax.

Chest-tube drainage seems to be a useful treatment for spontaneous pneumothorax, although RCT evidence is somewhat sparse.

• Small (8 French gauge) chest tubes are generally easier to insert, and may reduce the risk of subcutaneous emphysema, although successful resolution may be less likely in people with large pneumothoraces (>50% lung volume). We don't know whether there is a difference in duration of drainage with small tubes.

• The trials investigating the efficacy of adding suction to chest-tube drainage are too small and underpowered to detect a clinically important difference.

• We don't know whether using one-way valves on a chest tube is more effective than using drainage bottles with underwater seals. There is a suggestion, however, that one-way valves might reduce hospital admission and the need for analgesia.

It seems that needle aspiration might be beneficial in treating people with spontaneous pneumothorax, although it is not clear whether it is more effective than chest-tube drainage.

Pleurodesis seems to be effective in preventing recurrent spontaneous pneumothorax, although there are some adverse effects associated with the intervention.

• Chemical pleurodesis successfully reduces recurrence of spontaneous pneumothorax, although the injection has been reported to be intensely painful.

• Thoracoscopic surgery with talc instillation also seems to reduce recurrence of spontaneous pneumothorax, but leads to a modest increase in pain during the first 3 days.

• Video-assisted thoracoscopic surgery, while less invasive than thoracotomy, may be associated with higher recurrence rates.

• We found no RCT evidence examining when pleurodesis should be given, although there is general consensus that it is warranted after the second or third episode of spontaneous pneumothorax.

About this condition

Definition

A pneumothorax is air in the pleural space. A spontaneous pneumothorax occurs when there is no provoking factor — such as trauma, surgery, or diagnostic intervention. It implies a leak of air from the lung parenchyma through the visceral pleura into the pleural space, which causes the lung to collapse and results in pain and shortness of breath. This review does not include people with tension pneumothorax.

Incidence/ Prevalence

In a survey in Minnesota, USA, the incidence of spontaneous pneumothorax was 7/100,000 for men and 1/100,000 for women. In England and Wales, the overall rate of people consulting with pneumothorax (in both primary and secondary care combined) is 24/100,000 a year for men and 10/100,000 a year for women. The overall annual incidence of emergency hospital admissions for pneumothorax in England and Wales is 16.7/100,000 for men and 5.8/100,000 for women. Smoking increases the likelihood of spontaneous pneumothorax by 22 times for men and by 8 times for women. The incidence is directly related to the amount smoked.

Aetiology/ Risk factors

Primary spontaneous pneumothorax is thought to result from congenital abnormality of the visceral pleura, and is typically seen in young, otherwise fit people. Secondary spontaneous pneumothorax is caused by underlying lung disease, typically affecting older people with emphysema or pulmonary fibrosis.

Prognosis

Death from spontaneous pneumothorax is rare, with UK mortality of 1.26 per million a year for men and 0.62 per million a year for women. Published recurrence rates vary. One cohort study in Denmark found that, after a first episode of primary spontaneous pneumothorax, 23% of people had a recurrence within 5 years, most of them within 1 year. Recurrence rates had been thought to increase substantially after the first recurrence, but one retrospective case-control study (147 US military personnel) found that 28% of men with a first primary spontaneous pneumothorax had a recurrence; 23% of the 28% had a second recurrence; and 14% of that 23% had a third recurrence, resulting in a total recurrence rate of 35%.

Aims of intervention

To reduce morbidity; to restore normal function as quickly as possible; to prevent recurrence and mortality, with minimum adverse effects.

Outcomes

Successful resolution of spontaneous pneumothorax after a stated period; time to full expansion of the lung; duration of hospital stay; time off work; adverse effects of treatments (complications including pain, surgical emphysema, wound, and pleural space infection); and rate of recurrence.

Methods

Clinical Evidence search and appraisal January 2010. The following databases were used to identify studies for this systematic review: Medline 1966 to January 2010, Embase 1980 to January 2010, and The Cochrane Database of Systematic Reviews 2009, Issue 4 (1966 to date of issue). An additional search within The Cochrane Library was carried out for the Database of Abstracts of Reviews of Effects (DARE) and the Health Technology Assessment (HTA) database. We also searched for retractions of studies included in the review. Abstracts of the studies retrieved from the initial search were assessed by an information specialist. Selected studies were then sent to the contributor for additional assessment, using predetermined criteria to identify relevant studies. Study design criteria for inclusion in this review were: published systematic reviews of RCTs and RCTs in any language. RCTs had to contain 20 or more individuals of whom 80% or more were followed up. Blinded and non-blinded studies were included. There was no minimum length of follow-up required to include studies. We included systematic reviews of RCTs and RCTs where harms of an included intervention were studied applying the same study design criteria for inclusion as we did for benefits. In addition we use a regular surveillance protocol to capture harms alerts from organisations such as the FDA and the MHRA, which are added to the reviews as required. To aid readability of the numerical data in our reviews, we round many percentages to the nearest whole number. Readers should be aware of this when relating percentages to summary statistics such as relative risks (RRs) and odds ratios (ORs). We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table). The categorisation of the quality of the evidence (high, moderate, low, or very low) reflects the quality of evidence available for our chosen outcomes in our defined populations of interest. These categorisations are not necessarily a reflection of the overall methodological quality of any individual study, because the Clinical Evidence population and outcome of choice may represent only a small subset of the total outcomes reported, and population included, in any individual trial. For further details of how we perform the GRADE evaluation and the scoring system we use, please see our website (www.clinicalevidence.com).

Table.

GRADE Evaluation of interventions for Spontaneous pneumothorax.

Important outcomes	Duration of hospital stay, Recurrence rates, Resolution rates
Studies (Participants)	Outcome	Comparison	Type of evidence	Quality	Consistency	Directness	Effect size	GRADE	Comment
What are the effects of treatments in people presenting with spontaneous pneumothorax?
1 (18)	Resolution rates	Needle aspiration versus observation	4	−2	0	0	0	Low	Quality points deducted for sparse data and incomplete reporting of results
3 (194)	Resolution rates	Needle aspiration versus chest-tube drainage	4	−2	0	−1	0	Very low	Quality points deducted for sparse data and incomplete reporting of results. Directness point deducted for differences in definition of outcome
3 (194)	Duration of hospital stay	Needle aspiration versus chest-tube drainage	4	−1	0	0	0	Moderate	Quality point deducted for sparse data
3 (194)	Recurrence rates	Needle aspiration versus chest-tube drainage	4	−2	0	0	0	Low	Quality points deducted for sparse data and incomplete reporting of results
1 (26)	Resolution rates	Small- versus standard-sized chest tubes	4	−1	0	0	0	Moderate	Quality point deducted for sparse data
1 (30)	Resolution rates	One-way valves on chest tubes	4	−1	0	0	0	Moderate	Quality point deducted for sparse data
1 (30)	Duration of hospital stay	One-way valves on chest tubes	4	−1	0	0	+1	High	Quality point deducted for sparse data. Effect size point added for RR <0.5
1 RCT and one trial (93)	Resolution rates	Chest-tube drainage plus suction versus chest-tube drainage alone	4	−3	0	−2	0	Very low	Quality points deducted for sparse data, incomplete reporting of results, and inclusion of controlled clinical trial. Directness points deducted for not stating suction pressures used, and not stating whether primary or secondary spontaneous pneumothorax
What are the effects of interventions to prevent recurrence in people with previous spontaneous pneumothorax?
2 (325)	Recurrence rates	Adding chemical pleurodesis to chest-tube drainage versus chest-tube drainage alone	4	−2	0	0	0	Low	Quality points deducted for incomplete reporting of results and for open-label RCT
2 (325)	Duration of hospital stay	Adding chemical pleurodesis to chest-tube drainage versus chest-tube drainage alone	4	−2	0	0	0	Low	Quality points deducted for incomplete reporting of results and for open-label RCT
1 (108)	Recurrence rates	Thoracoscopic surgery with talc instillation versus chest-tube drainage	4	−1	0	0	0	Moderate	Quality point deducted for sparse data
1 (108)	Duration of hospital stay	Thoracoscopic surgery with talc instillation versus chest-tube drainage	4	−2	0	0	0	Low	Quality points deducted for sparse data and incomplete reporting of results
3 (210)	Recurrence rates	Video-assisted thoracoscopic surgery versus thoracotomy	4	−1	0	0	0	Moderate	Quality point deducted for incomplete reporting of results
3 (263)	Duration of hospital stay	Video-assisted thoracoscopic surgery versus thoracotomy	4	−1	−1	0	0	Low	Quality point deducted for incomplete reporting of results. Consistency point deducted for conflicting results

We initially allocate 4 points to evidence from RCTs, and 2 points to evidence from observational studies. To attain the final GRADE score for a given comparison, points are deducted or added from this initial score based on preset criteria relating to the categories of quality, directness, consistency, and effect size. Quality: based on issues affecting methodological rigour (e.g., incomplete reporting of results, quasi-randomisation, sparse data [<200 people in the analysis]). Consistency: based on similarity of results across studies. Directness: based on generalisability of population or outcomes. Effect size: based on magnitude of effect as measured by statistics such as relative risk, odds ratio, or hazard ratio.

Glossary

French gauge

A measure of the size of a catheter or drainage tube defined (in France by JFB Charrière in 1842) to be the outside diameter of the tube in units of 1/3 mm. A 12 French gauge tube has an outer diameter of 4 mm. Sometimes the French gauge is called the Charrière (Ch) gauge.

High-quality evidence

Further research is very unlikely to change our confidence in the estimate of effect.

Low-quality evidence

Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.

Moderate-quality evidence

Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.

Very low-quality evidence

Any estimate of effect is very uncertain.

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