Journal of

Clinical Medicine

Review
Chest Tube Drainage Versus Conservative
Management as the Initial Treatment of Primary
Spontaneous Pneumothorax: A Systematic Review
and Meta-Analysis
Jong Hyuk Lee 1,† , Ryul Kim 2,† and Chang Min Park 1, *
1 Department of Radiology, Seoul National University Hospital, Seoul National College of Medicine,
Seoul 03080, Korea; lee87jh@gmail.com
2 Department of Internal Medicine, Seoul National University Hospital, Seoul National College of Medicine,
Seoul 03080, Korea; chrono0707@kaist.ac.kr
* Correspondence: cmpark.morphius@gmail.com; Tel.: +82-2-2072-0367; Fax: +82-2-743-6386
† Jong Hyuk Lee and Ryul Kim contributed equally to this research as first authors.




Received: 5 October 2020; Accepted: 26 October 2020; Published: 27 October 2020


Abstract: Objectives: This systematic review and meta-analysis aimed to compare chest tube drainage
and conservative management as the initial treatment of primary spontaneous pneumothorax (PSP).
Methods: Studies including PSP patients who received tube drainage or conservative management
as the initial treatment were searched in OVID-MEDLINE and Embase through 14 February 2020.
The primary outcome was the relative risk (RR) of PSP recurrence, and secondary outcomes were
RRs of PSP resolution and adverse events during treatment. A random-effect model using the
Mantel–Haenszel method was used to pool RRs. Subgroup and meta-regression analyses were
performed to investigate significant predictors of PSP recurrence. Results: In total, 11,922 PSP
cases from eight studies were analysed, of which 6344 were treated with tube drainage and 5578
were treated with conservative management. The pooled RR of PSP recurrence for conservative
management against tube drainage was 0.98 (95% confidence interval [CI], 0.75–1.28; p = 0.894).
Subgroup and meta-regression analyses revealed that study design (p = 0.816), allocation of the PSP
amount in each management group (p = 0.191), and assessment time for recurrence had no significant
impact on PSP recurrence (p = 0.816). There was no publication bias (p = 0.475). The risk of adverse
events of conservative management was significantly lower than that of tube drainage (pooled RR,
0.22; 95% CI, 0.08–1.15; p = 0.003). However, no difference was found between the two groups in
terms of PSP resolution (pooled RR, 1.01; 95% CI, 0.9–1.15; p = 0.814). Conclusions: As the initial
treatment for PSP, conservative management is comparable to chest tube drainage in terms of PSP
recurrence and resolution after treatment, with fewer adverse events during treatment.

Keywords: pneumothorax; conservative treatment; tube drainage; recurrence; complications

1. Introduction
Primary spontaneous pneumothorax (PSP), which refers to spontaneous pneumothorax in
otherwise healthy people, is a significant health problem, with a reported annual incidence of 7.4 per
100,000 men and 1.2 per 100,000 women [1–3]. PSP is a disease of young people and the recurrence
rate of PSP after complete resolution by appropriate management is quite high, with reported rates
of 29% within 1 year and 32.1% during the lifetime [3]. Although various parameters, including
age, body weight, height, smoking, and bullae or pleural thickening on computed tomography

J. Clin. Med. 2020, 9, 3456; doi:10.3390/jcm9113456 www.mdpi.com/journal/jcm

J. Clin. Med. 2020, 9, 3456 2 of 10

examinations, have been postulated as factors potentially influencing PSP recurrence, there is a lack of
consensus on which factors are truly associated with PSP recurrence [3–10].
Recently, a randomized controlled trial (RCT) suggested that recurrence of PSP was more frequent
in patients treated with chest tube drainage than in those who received conservative management [11].
Nevertheless, considerable heterogeneity remains in the management for PSP, even among authoritative
guidelines [1,2]. For large PSP, the American College of Chest Physicians (ACCP) recommends
chest tube drainage to expand the lung [2], while the British Thoracic Society (BTS) suggests that
asymptomatic patients may be managed by observation alone, with chest tube drainage reserved
for only physiologically unstable patients [1]. A systematic review with a meta-analysis is therefore
needed to answer the question of which treatment option—chest tube drainage or conservative
management—is better in terms of the recurrence of PSP. Thus, we aimed to conduct a comprehensive
review and comparison of chest tube drainage and conservative management as the initial treatment
of PSP in terms of recurrence after treatment, resolution, and adverse events during treatment.

2. Experimental Section
This systematic review was performed and reported in compliance with the Preferred Reporting
Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

2.1. Search Strategy

We searched the Embase and OVID-MEDLINE databases to identify relevant publications with
the following search terms: (pneumothorax OR pneumothoraces) AND (primary OR spontaneous)
AND (intervention* OR conservativ* OR observati*). The initial search was undertaken on 14 February
2020. We included all articles published in English without any limits on publication year.

2.2. Eligibility Criteria for Study Selection

We reviewed all the retrieved publications regardless of the study type. The inclusion criteria
were as follows: (a) RCTs, prospective or retrospective cohort studies, and case-control studies dealing
with PSP, not letters, editorial comments, abstracts, conference materials, case reports, case series,
review articles, guidelines, consensus statements, or study protocols; (b) studies with unilateral PSP
patients; (c) studies that compared chest tube drainage and conservative management as the initial
treatment of PSP; and (d) data described in sufficient detail to extract the final outcomes in terms of
PSP recurrence, PSP resolution, and adverse events during the treatment. We excluded studies dealing
with secondary spontaneous pneumothorax.
Full-text articles were assessed for eligibility independently by two authors (J.H.L. and R.K.).
Any discrepancy was resolved by consensus.

2.3. Data Extraction

The following items were extracted from the articles: name of the first author, title of the study,
year of publication, study design (prospective vs. retrospective), assessment time for recurrence of
PSP, PSP amount in each treatment group, total number of patients, PSP recurrence after treatment,
PSP resolution, and adverse events related with the treatment. To avoid errors in the data extraction
process, two authors (J.H.L. and R.K.) independently reviewed all eligible articles, extracted the
abovementioned data, and compared their results. All data were checked for internal consistency,
and disagreements between the two authors were resolved by discussion. In addition to this review
process, we tried to contact the corresponding authors of each study via e-mail for missing or
unreported data.
J. Clin. Med. 2020, 9, 3456 3 of 10

2.4. Assessment of Risk of Bias

Randomized studies included in this study were assessed using the Cochrane risk of bias tool [12].
Bias was assessed over the following pre-specified domains: random sequence generation, concealment
of allocation, blinding, completeness of outcome data, and selective reporting. For assessing the quality
of nonrandomized studies, the Newcastle–Ottawa scale was used to evaluate the following three
pre-specified domains: selection, comparability, and outcomes [13].

2.5. Statistical Analysis

The primary outcome of this study was the recurrence rate of PSP after treatment, defined as the
occurrence of ipsilateral pneumothorax after the complete resolution of the previous PSP. Secondary
outcomes included the resolution rate of PSP, defined as the rate of patients with complete resolution
of PSP, and the rate of adverse events, defined as complications related with the treatment (e.g., severe
chest pain, haemothorax, empyema, or subcutaneous emphysema).
Because the study population and the characteristics of the cases of pneumothorax included in
this study were considered heterogeneous, a random-effect model using the Mantel–Haenszel method
was used to calculating pooled relative risks (RRs), 95% confidence intervals (95% CIs), and p-values.
Heterogeneity across the included studies was evaluated using the I2 statistic, which was derived
from the Cochran Q statistic using the following equation, I2 = 100% (Q-df)/Q. An I2 statistic >50%
was regarded as indicating substantial heterogeneity. Subgroup analysis and meta-regression were
performed to investigate the causes of heterogeneity with the following covariates: study design
(prospective vs. retrospective), allocation of the PSP amount in each management group (equally
allocated study vs. non-equally allocated study), and assessment time for recurrence (within 12 months
vs. after 12 months). The potential for publication bias was evaluated with a visual assessment of funnel
plots of the standard error against the RR, using the Egger regression test of funnel plot asymmetry [14].
A p value of <0.05 was considered to indicate a statistically significant difference. All statistical
analyses were performed using R version 4.0.0 (R Project for Statistical Computing, Vienna, Austria).

3. Results

3.1. Eligible Studies

The search of electronic databases resulted in a total of 3733 studies. After excluding 705 duplicate
articles, the abstracts of 3028 studies were examined for relevance to the inclusion criteria and
3003 studies were excluded (study not in the field of interest, n = 2274; inappropriate study type,
n = 710; not written in English, n = 19). The remaining 25 studies were thoroughly reviewed in
detail and 15 studies were additionally excluded (no information about PSP recurrence, n = 10;
study dealing with both PSP and secondary spontaneous pneumothorax, n = 4; overlapping study
population, n = 1). Finally, 10 studies were eligible for the analyses of recurrence of PSP after treatment
(n = 8) [6,9,11,15–19], resolution of PSP (n = 3) [11,20,21], and adverse events during treatments (n = 3)
(Table 1 and Figure 1) [11,16,21].
J. Clin. Med. 2020, 9, 3456 4 of 10

Table 1. Characteristics of studies included in the meta-analysis.

Allocation of the Assessment Recurrence Recurrence Resolution Resolution Adverse Event Adverse Event
Inclusion
Authors Years Study Design PSP Amount in Each Time of PSP (Conservative (Chest Tube (Conservative (Chest Tube (Conservative (Chest Tube
of Outcome
Management Group Recurrence Management) Drainage) Management Drainage) Management Drainage)
Prospective
Alfageme I et al. 1994 Non-equal Within 12 months Recurrence 7/21 11/34 N/A N/A N/A N/A
cohort
Retrospective
Kelly AM et al. 2008 Non-equal N/A Resolution N/A N/A 72/91 47/64 N/A N/A
cohort
Retrospective
Ganesalingam R et al. 2010 Equal After 12 months Recurrence 4/5 50/95 N/A N/A N/A N/A
cohort
Resolution,
Retrospective
Kuan WS et al. 2011 Non-equal N/A adverse N/A N/A 15/22 21/40 0/22 5/40
cohort
events
Recurrence,
Retrospective
Chew R et al. 2014 Equal After 12 months adverse 6/53 6/58 N/A N/A 0/53 16/58
cohort
events
Retrospective
Kim et al. 2014 Non-equal After 12 months Recurrence 2/16 7/39 N/A N/A N/A N/A
cohort
Prospective
Olsen WH et al. 2016 Non-equal Within 12 months Recurrence 16/23 126/234 N/A N/A N/A N/A
cohort
Retrospective
Huang YH et al. 2017 Non-equal After 12 months Recurrence 1139/5277 1462/5679 N/A N/A N/A N/A
cohort
Recurrence,
Randomized resolution,
Brown SGA et al. 2020 Equal Within 12 months 14/159 25/149 118/125 129/131 13/162 41/154
controlled trial adverse
events
Retrospective
Balta C et al. 2020 Non-equal Within 12 months Recurrence 0/24 2/56 N/A N/A N/A N/A
cohort
PSP, primary spontaneous pneumothorax; N/A, not available.
J. Clin. Med. 2020, 9, 3456 5 of 10
J. Clin. Med. 2020, 9, x FOR PEER REVIEW 5 of 10

Figure Flow diagram

1. Flow
Figure 1. diagramof
ofthe
theliterature
literaturesearch.
search.
J. Clin. Med. 2020, 9, 3456 6 of 10

J. Clin. Med. 2020, 9, x FOR PEER REVIEW 6 of 10

Regarding the risk of bias, in one RCT, the participants and staff were not blinded to the type
Regarding the risk of bias, in one RCT, the participants and staff were not blinded to the type of
of treatment that each participant received because of the open-label study design [11]. All nine
treatment that each participant received because of the open-label study design [11]. All nine
nonrandomized studies had a high risk of bias in terms of comparability, and their median score was 6
nonrandomized studies had a high risk of bias in terms of comparability, and their median score was
(range, 4–7).
6 (range, 4–7).
3.2. Recurrence of PSP after Treatment
3.2. Recurrence of PSP after Treatment
Eight studies
Eight studies with
with11,922
11,922PSPPSPcases
caseswere
were eligible
eligible for assessingthe
for assessing thedifference
differenceininpneumothorax
pneumothorax
recurrence after treatment [6,9,11,15–19]. Conservative management was
recurrence after treatment [6,9,11,15–19]. Conservative management was provided in 5578 provided in 5578PSPPSP cases,
cases,
of which
of which 1188
1188(21.3%
(21.3% ofof
5578
5578cases)
cases)had
hadrecurrence
recurrence after
after treatment.
treatment. In Incontrast,
contrast,the
theother
other6344
6344 cases
cases
were
weretreated
treatedwith
withchest
chesttube
tubedrainage,
drainage,ofofwhich
which 1690
1690 had
had recurrence (26.6%). The
recurrence (26.6%). Thepooled
pooledRRRR of of
recurrence
recurrence in the conservative management group relative to the tube drainage group was 0.98 (95%CI,
in the conservative management group relative to the tube drainage group was 0.98 (95%
0.75–1.28; p = 0.894;
CI, 0.75–1.28; I2 = 57%)
p = 0.894; (Figure
I2 = 57%) 2A). Subgroup
(Figure 2A). Subgroupand meta-regression
and meta-regression analyses revealed
analyses that that
revealed study
design
study = 0.816),
(p design (p allocation of the PSPofamount
= 0.816), allocation the PSPinamount
each management group (p =group
in each management 0.191),(pand assessment
= 0.191), and
assessment
time for recurrence (p =recurrence
time for 0.816) did(p = have
not 0.816)a did not have
significant a significant
impact impact on pneumothorax
on pneumothorax recurrence after
recurrence after treatment. (Supplementary Table S1 and Supplementary
treatment. (Supplementary Table S1 and Supplementary Figure S1). Specifically, in the subgroupFigure S1). Specifically, in
the subgroup
analysis of studiesanalysis of studies
assessing assessing
recurrence recurrence
of PSP withinof12PSP withinthe
months, 12 pooled
months,RR thefor
pooled RR for
conservative
conservative management compared to chest tube drainage was 0.9 (95% CI,
management compared to chest tube drainage was 0.9 (95% CI, 0.75–1.28). There was no publication 0.75–1.28). There was
no publication bias according to the funnel plots (p = 0.475;
bias according to the funnel plots (p = 0.475; Supplementary Figure S2). Supplementary Figure S2).

(A)

(B)

(C)
Figure
Figure 2. 2.Forest
Forestplot
plotcomparing
comparingconservative
conservative management
management and and chest
chesttube
tubedrainage
drainagefor
forprimary
primary
spontaneous
spontaneous pneumothorax
pneumothorax (PSP).
(PSP). (A)(A) Recurrence
Recurrence of PSP,
of PSP, (B) resolution
(B) resolution of PSP,
of PSP, andadverse
and (C) (C) adverse
events
events
during during treatment.
treatment.
J. Clin. Med. 2020, 9, 3456 7 of 10

3.3. PSP resolution and Treatment-Related Adverse Events

Three studies with 473 PSP cases were eligible for estimating the RR of PSP resolution [11,20,21].
Two hundred thirty-eight cases received conservative management and the remaining 235 cases
underwent chest tube drainage as the initial treatment for PSP. Resolution of PSP occurred in 205
(86.1%) and 197 (83.8%) cases in the conservative management group and tube drainage group,
respectively. The pooled RR for PSP resolution of conservative management relative to chest tube
drainage was 1.01 (95% CI, 0.9–1.15; p = 0.814; I2 = 42%) (Figure 2B). In the subgroup and meta-regression
analyses, study type (p = 0.094) and allocation of the PSP amount in each management group (p = 0.094)
had no significant impact on PSP resolution (Supplementary Table S1 and Supplementary Figure S3).
The analysis of treatment-related adverse events included 489 PSP cases from three studies [11,16,21].
Adverse events during treatment occurred in 13 of the 237 PSP cases receiving conservative management
(5.5%) and in 62 of the 252 cases (24.6%) receiving chest tube drainage. The pooled RR of adverse
events of conservative management relative to chest tube drainage was 0.22 (95% CI, 0.082–0.591;
p = 0.003; I2 = 18%), demonstrating that the conservative management group had significantly fewer
treatment-related adverse events than the chest tube drainage group (Figure 2C). Although there was
no heterogeneity in the subgroup analysis according to the study design (I2 = 0%), heterogeneity
was identified regarding the allocation of the PSP amount in each management group (I2 = 57%)
(Supplementary Table S1 and Supplementary Figure S4). The most common adverse events were
severe chest pain or shortness of breath in both the conservative management group (n=4) and the
chest tube drainage group (n = 11). Haemothorax and empyema occurred in both the conservative
management group (haemothorax, n = 3; empyema, n = 1) and the tube drainage group (haemothorax,
n = 10; empyema, n = 4). Tension pneumothorax was only reported in the chest tube drainage group
(n = 3).

4. Discussion
Since PSP occurs mainly in young people and recurrence is common, patients with PSP may present
to hospitals with recurrent PSP multiple times in their lives [3,22,23]. For this reason, PSP treatment
should seek to minimise the recurrence rate, and it would also be ideal to use a treatment method
that improves the likelihood of PSP resolution while reducing the risk of treatment-related adverse
events. To our knowledge, no systematic review has compared PSP recurrence between conservative
management and chest tube drainage as the initial treatment of PSP. In this systematic review and
meta-analysis, we demonstrated that patients who received conservative management showed a
comparable rate of PSP recurrence (pooled RR, 0.98; 95% CI, 0.75–1.28) and PSP resolution (pooled RR,
1.01; 95% CI, 0.9–1.15) to those who underwent chest tube drainage, but with fewer treatment-related
adverse events (pooled RR, 0.22; 95% CI, 0.08–0.59).
Although asymptomatic patients with small PSP can be managed conservatively, there has
been substantial heterogeneity in the management of moderate to large PSP [1]. Regarding cases of
moderate to large PSP, the ACCP guideline recommends an invasive intervention with a small-bore
catheter or chest tube to expand the lung [2], while the BTS suggests conservative management with
observation, with chest drainage reserved for only physiologically significant patients [1]. Indeed,
chest tube drainage has traditionally been considered the definitive treatment for PSP and has been
the main procedure used for PSP treatment [1,2], but previous studies have also reported evidence
supporting conservative management [15,22–24]. The choice of a treatment option for PSP is clinically
relevant since chest tube drainage can cause treatment-related complications, prolong hospitalization,
and put a financial burden on patients [11]. In this regard, our results support the concept that
conservative management can be used as the initial treatment option for PSP because it yields a
comparable recurrence and resolution rate of PSP, with fewer treatment-related adverse events than
those occurring after chest tube drainage. However, our results should not be interpreted as providing
evidence that conservative management can be applied to clinically significant symptomatic patients
J. Clin. Med. 2020, 9, 3456 8 of 10

or physiologically unstable patients. Those patients should immediately undergo active interventions
including chest tube insertion to manage their symptoms and physiological instability [1,2].
According to a prior systematic review dealing with the recurrence of PSP, interventional
procedures did not show a significant reduction in the recurrence rate compared to conservative
management (28.5% in the interventional procedure group vs. 21.9% in the conservative management
group; p = 0.353) [3]. However, the interventional procedure group of the prior study included
both needle aspiration and thoracostomy [3], but the ACCP guideline acknowledges that needle
aspiration is not appropriate for PSP management in any clinical circumstances [2]. Therefore, a study
comparing conservative management to only chest tube drainage, which is the definitive treatment
option for PSP, is needed [1,2]. In this context, our results could provide evidence that conservative
management is comparable to chest tube drainage in terms of recurrence after treatment, which implies
that conservative management can be an alternative to chest tube drainage in hemodynamically stable
PSP patients.
Although this meta-analysis revealed no significant difference in PSP recurrence between the
conservative management and chest tube drainage groups, our results still have limitations in that
there were only two studies in which the conservative management group and the tube drainage
group were equivalently allocated [11,16]. In the other six studies, the patients were not equivalently
allocated according to their PSP amount, and patients with small pneumothorax tended to be managed
conservatively [6,9,15,17–19]. In the analysis of PSP recurrence, heterogeneity across the eight studies
was 57%, and substantial heterogeneity remained even after adjusting for potential influencing factors
such as study design, allocation of the PSP amount in each management group, and assessment time for
recurrence. We must admit that it was very difficult to address every factor leading to this heterogeneity
because only one study was an RCT [11]. For the analysis of PSP resolution, only one study equally
assigned PSP cases into the two different management groups regardless of PSP amount [11]. The other
two studies had a tendency for small PSP patients to undergo conservative management, and for
patients with moderate or large PSP to receive chest tube drainage [19,20]. This may reflect the tendency
in clinical practice for patients with moderate to large PSP to undergo chest tube drainage and have the
accumulated air in the pleural cavity removed without any delay. To overcome this limitation, further
studies equivalently allocating PSP cases into conservative management and chest tube drainage
groups should be performed.
There are several other limitations of this study. First, there was only one RCT in this meta-analysis
and this might cause a risk of bias in that the data from RCTs and non-RCTs were treated equivalently.
The readers should pay attention to this limitation. Second, there was significant heterogeneity in
the methods used to measure the amount of PSP between studies, and we could not take this issue
into account. Third, only a small number of studies analysed PSP resolution and adverse events.
Therefore, the statistical power of these analyses might not be sufficient to draw firm conclusions.
Fourth, this review may not fully reflect advanced modern interventional techniques and medical
treatments, since we included all studies regardless of their publication year.

5. Conclusions
In conclusion, as the initial treatment for PSP, conservative management is comparable to chest
tube drainage in terms of PSP recurrence and resolution after treatment, with fewer adverse events
during treatment.

Supplementary Materials: The following are available online at http://www.mdpi.com/2077-0383/9/11/3456/s1,

Table S1: Meta-regression comparing conservative management and chest tube drainage for primary spontaneous
pneumothorax (PSP), Figure S1: Subgroup analysis comparing conservative management and chest tube drainage
in terms of primary spontaneous pneumothorax recurrence (PSP). (A) Study design, (B) allocation of the PSP size,
and (C) assessment time, Figure S2: Funnel plot of included studies evaluating recurrence of primary spontaneous
pneumothorax, Figure S3: Subgroup analysis comparing conservative management and chest tube drainage in
terms of primary spontaneous pneumothorax resolution (PSP). (A) Study design, (B) allocation of the PSP size,
J. Clin. Med. 2020, 9, 3456 9 of 10

Figure S4: Subgroup analysis comparing conservative management and chest tube drainage in terms of adverse
events during treatment. (A) Study design, (B) allocation of the primary spontaneous pneumothorax size.
Author Contributions: J.H.L., R.K. and C.M.P. contributed to the study concept and design, acquisition of the data,
analysis and interpretation of the data, and drafting of the manuscript. All authors contributed to critical revision
for relevant intellectual content and final approval of this manuscript. All authors are accountable for all aspects
of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately
investigated and resolved. All authors have read and agreed to the published version of the manuscript.
Funding: This research did not receive any specific grant from funding agencies in the public, commercial,
or not-for-profit sectors.
Acknowledgments: The authors would like to acknowledge Andrew Dombrowski (Compecs, Inc.) for his
assistance in improving the use of English in this manuscript.
Conflicts of Interest: The authors declare no conflict of interest.

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