Monday, May 14, 2007

Talc pleurodesis - safe with the right product

Talc pleurodesis - safe with the right product

Pleurodesis using a talc preparation produced specifically for the purpose is safe, and has a low incidence of severe adverse effects according to a prospective cohort study published in today's Lancet. Talc pleurodesis has been used for decades in the treatment of a range of pleural diseases; it is effective, cheap, and widely available. It has generally been considered to be safe, however reports of severe adverse effects including acute respiratory distress syndrome (ARDS) have raised questions over this. The authors of this study note that the incidence of severe adverse effects in case series has not been consistent, with no relationship to the underlying diseases being treated. As there is evidence that the incidence of adverse effects may relate to the particle size of the talc used, they carried out a prospective cohort study of patients treated with a commercially produced talc intended for pleurodesis and graded to include predominantly large particles (Steritalc). This product has a mean particle size of 24.5 microns and only 11% of particles are <5 microns.

The cohort included patients from 13 European and one South African hospitals. All underwent thorascopy and pleurodesis for malignant pleural effusions with 4 grams of insufflated talc given using a standardised technique. Other treatment and procedures were at the doctor's choice according to clinical need and local practice; all patients had a chest X-ray at baseline and within 24 hours of the procedure. The primary endpoint of the study was occurrence of ARDS; the authors estimated a maximum frequency of 1% for this based on previous reviews, and thus aimed to include at least 300 patients to show that the risk was no more than this.

An eventual total of 558 patients was eventually recruited into the study; their mean age was 64.4 (range 30 to 96), and the most frequent underlying condition was non-small cell lung cancer (41%). No patient developed ARDS. Eleven patients died within 30 days of the procedure, mostly due to consequences or progression of their underlying disease. One developed respiratory failure due to other causes and there were six other serious adverse events, however there were no serious pulmonary complications within the first 48 hours after the procedure. The authors conclude that large particle talc is safe for pleurodesis in patients with malignant pleural effusion, and is not associated with ARDS.

They discuss their results, noting that reports of ARDS have come from the US and Brazil, whereas reviews from Europe and Israel have not found any cases. Evidence suggests that talc preparations containing a high proportion of small particles are more likely to cause adverse effects. In view of this, the authors considered that a comparative study of small-particle and large particle talc would be unethical, hence their choice of a prospective cohort study. Based on their data, they consider that ARDS would develop after pleurodesis with large-particle talc in no more than 6 patients per thousand.

An accompanying Comment discusses the study.

Lancet 2007; 369: 1535-9 (link to abstract); Lancet 2007; 369: 1494-6 (Comment; link to full text, available to subscribers only)

No comments: