Survival in Patients With Malignant Pleural Effusions Who Developed Pleural Infection: A Retrospective Case Review From Six UK Centers

Our plain-English summary of Survival in Patients With Malignant Pleural Effusions Who Developed Pleural Infection: A Retrospective Case Review From Six UK Centers, by A.C. Bibby, A.O. Clive, G.C. Slade, et al (Chest, 2015).

The study

• Authors: A.C. Bibby, A.O. Clive, G.C. Slade, A.J. Morley, J. Fallon, I. Psallidas, J.C.T. Pepperell, M.G. Slade, A.E. Stanton, N.M. Rahman, N.A. Maskell
• Journal: Chest
• Published: 2015;148(1):235-241
• Cited by: 34 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: Malignant pleural effusion (MPE) incidence is increasing, and prognosis remains poor. Indwelling pleural catheters (IPCs) relieve symptoms but increase the risk of pleural infection. We reviewed cases of pleural infection in patients with IPCs for MPE from six UK centers between January 1, 2005, and January 31, 2014.

Methods: Survival in patients with pleural infection was compared with 788 patients with MPE (known as the LENT [pleural fluid lactate dehydrogenase, Eastern Cooperative Oncology Group performance status, serum neutrophil to lymphocyte ratio, and tumor type] cohort) and with national statistics.

Results: Of 672 IPCs inserted, 25 (3.7%) became infected. Most patients (20 of 25) had mesothelioma or lung cancer. Median survival in the pleural infection cohort appeared longer than in the LENT cohort, although this result did not achieve significance (386 days vs 132 days; hazard ratio, 0.67; P = .07). Median survival with mesothelioma and pleural infection was twice as long as national estimates for mesothelioma survival (753 days vs < 365 days) and double the median survival of patients with mesothelioma in the LENT cohort (339 days; 95% CI, nonoverlapping). Survival with lung and breast cancer did not differ significantly between the groups. Sixty-one percent of patients experienced early infection. There was no survival difference between patients with early and late infection (P = .6).

Conclusions: This small series of patients with IPCs for MPE suggests pleural infection may be associated with longer survival, particularly in patients with mesothelioma. Results did not achieve significance, and a larger study is needed to explore this relationship further and investigate whether the local immune response, triggered by infection, is able to modulate mesothelioma progression.

In plain English

This study looked back at records from six UK hospitals. It covered patients with malignant pleural effusion (fluid around the lung caused by cancer) who had an indwelling pleural catheter, a drainage tube left in place, inserted between January 2005 and January 2014. Of 672 catheters, 25 (3.7%) became infected. Most of these patients had mesothelioma or non-small cell lung cancer. Their survival was compared with a separate group of 788 patients with malignant pleural effusion, called the LENT cohort, and with national figures. Median survival was 386 days in the infection group and 132 days in the LENT cohort. This difference was not statistically significant (hazard ratio 0.67, 95% CI 0.43 to 1.03, P value 0.07). Among 11 patients with mesothelioma, median survival was 753 days, compared with 339 days for mesothelioma patients in the LENT cohort. The article does not report asbestos exposure. The authors concluded that pleural infection may be associated with longer survival, particularly in mesothelioma, and that a larger study is needed. They noted the small numbers, the lack of a true control group, and possible confounding.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective case review (audit of practice) of pleural infection cases from six UK centers, with survival compared against an external prospectively collected cohort (LENT cohort) and national statistics; not a formal case-control study
• Who was studied: Patients who had indwelling pleural catheters inserted for malignant pleural effusion in six UK centers between January 1, 2005 and January 31, 2014. Of 672 catheters, 25 patients developed pleural infection (19 male, 6 female, median age 69). Tumor types were mesothelioma 12, non-small cell lung cancer 8, breast 3, lymphoma 1 and thyroid 1. The comparison group was 788 patients with malignant pleural effusion from three international pleural centers (LENT cohort).
• Exposure: Pleural infection in patients with an indwelling pleural catheter, defined as clinical symptoms and signs needing antibiotic treatment, with or without positive pleural fluid microscopy or culture. Superficial wound infections at the insertion site were not included. Asbestos exposure was not studied.
• Main results:
  • Of 672 indwelling pleural catheters inserted, 25 (3.7%) became infected.
  • Median survival in the pleural infection group was 386 days (95% CI, 302-684), compared with a median of 132 days in the LENT cohort.
  • Survival curves showed longer survival in the pleural infection group, but the difference did not reach statistical significance (hazard ratio 0.67; 95% CI, 0.43-1.03; P value 0.07).
  • Among 11 patients with mesothelioma and pleural infection, median survival was 753 days (95% CI 446-1,089). Mesothelioma patients in the LENT cohort (170 patients) had a median of 339 days (95% CI 267-442).
  • One-year survival for the mesothelioma patients with pleural infection was 82%. The authors compared this with US and UK 1-year survival rates of under 40%.
  • Patients with pleural infection and non-small cell lung cancer (7 patients, median 138 days) had longer median survival than LENT cohort patients with non-small cell lung cancer, but the confidence intervals overlapped.
  • Survival with breast cancer was similar in the pleural infection group (3 patients) and the LENT cohort.
  • Of 13 patients for whom LENT scores could be calculated, 9 (69%) lived longer than their LENT score-predicted median life expectancy.
  • Survival did not differ between patients infected within 90 days of catheter insertion and those infected later. Medians were 209 days (95% CI 196-779) and 504 days (95% CI 291-760); hazard ratio 1.06, P value 0.91.
  • Three of the 25 patients (12%) died within 30 days of being diagnosed with pleural infection.
• The authors' conclusion: The authors concluded that this small series suggests pleural infection may be associated with longer survival, particularly in patients with mesothelioma. Statistical significance was not achieved, and they stated that a larger study is needed to confirm this and to look at whether the immune response triggered by infection might affect mesothelioma progression.
• Limitations the authors state:
  • Small sample size. The numbers were too small for multivariate modeling.
  • Cases were identified retrospectively, which depended on complete record keeping and could have introduced recall bias.
  • There was no control group of catheter patients without infection. The LENT cohort was used as a comparator instead, and differences between the two groups may have introduced bias.
  • Whether patients in the LENT cohort had pleural infection was not known.
  • The longer survival may reflect confounding by indication. Early on, catheters were offered to patients expected to live longest, and only 15% of the LENT cohort had a catheter.
  • The predominance of the epithelial subtype of mesothelioma in the study group may have skewed survival times upward.
  • Pleurodesis data were missing for some patients.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Prognosis, Indwelling Pleural Catheter, Lactate Dehydrogenase (LDH), Performance Status, Mesothelioma, Lung Cancer, Median Survival.

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