From the authors:
We read with interest the correspondence by B. Houltz and co-workers in which they comment on the recently suggested update of an algorithm for the functional assessment before lung resection, which forms part of the European Respiratory Society (ERS)/European Society of Thoracic Surgeons (ESTS) clinical guidelines on fitness for radical therapy in lung cancer patients (surgery and chemo-radiotherapy 1. This algorithm, originally proposed in 1998 2, is based on four key parameters: 1) a cardiac evaluation according to time-honoured principles well-known in the cardiology literature (ECG, stress ECG, etc.); 2) a pulmonary evaluation with assessment of pulmonary mechanics using spirometry (forced expiratory volume in 1 s; FEV1); 3) a pulmonary evaluation with assessment of gas exchange using the diffusing capacity of the lung for carbon monoxide (DL,CO); and 4) for patients who do not qualify/disqualify for a given amount of resection after these initial tests, a combined cardio-pulmonary exercise test with the determination of peak oxygen uptake (V′O2,peak) is proposed. While B. Houltz and co-workers agree with all parameters used in the algorithm, they query the use of percent of predicted values for the variable age, while not contesting them for sex, height and weight. They argue that correction for age is inappropriate as the normal age-related decline in lung function and exercise capacity is ignored. Interestingly, we do not ignore this decline; on the contrary, this decline is used in order not to rule out older people from resections simply because their absolute values for a given parameter have declined. To use the example given by B. Houltz and co-workers: the new lowest cut-off for safe resection of pulmonary tissue proposed by the ERS/ESTS Task Force is 30% post-operative predicted (ppo) for FEV1 and DL,CO, which for the 70-yr-old male would amount to 0.9 L for FEV1 3. If this male was aged 25 yrs 0.9 L would only be 20% of predicted, therefore, B. Houtlz and co-workers argue that 20% ppo adjusted for 25 yrs be used for all ages for FEV1, and also for DL,CO and V′O2,peak.
This suggestion implies that irrespective of age one needs a certain absolute value and, therefore, younger people could have a lower functional reserve when expressed in predicted values. Although this suggestion sounds interesting, we would definitely like to caution against its use. First, we are not aware of any published data supporting this view and secondly lowering the ppo values for FEV1 and DL,CO from the original 40% suggested in 1998 2 to 30% 1 is a major step and needs prospective validation in larger studies. The suggested lowering of this cut-off value to 20% adjusted for 25 yrs of age may well put young people at an unacceptable risk. A young person most likely needs higher absolute values to qualify for safe resection; in other words, a 25-yr-old patient with 20% ppo function for FEV1 has much more unhealthy lungs than a 70-yr-old patient with a ppo value of 30%, although in absolute values they both have 0.9 L.
The current use of percent of predicted values has been shown to work well and, generally speaking, guidelines should suggest cut-off values which err on the side of safety. The trend to include more patients with marginal cardio-pulmonary functional reserves for resection will continue 4, but must be based on evidence.
Statement of interest
None declared.
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