Study	Reason for exclusion
Adelroth 1998	Review article.
Arnold 1990	No placebo arm. Study compared enprofylline versus theophylline.
Ashutosh 1997	The objective of this study was to observe the effect theophylline on respiratory drive. The study was also only of single doses of theophylline.
Bachmann 1995	All patients were taking theophylline as study was seeing the effects of cimetidine and famotidine on theophylline.
Berry 1991	Because of the objective of this study is investigate the effect to theophylline on sleep‐disordered breathing in patients with COPD.
Beulcke 1995	No placebo arm. Study compared two derivatives of xanthine.
Bleecker 1991	Single dose study lasting 2 hours and probably not an RCT.
Blom 1985	Study did not involve the use of theophylline.
Boos 1989	No placebo arm in study.
Carvalho‐Pinto 1991	No placebo arm in study.
Chapman 1990	The population studied had reversible obstructive airway disease (asthma)
Conradson 1987	The population studied have bronchial asthma (23) and/or chronic bronchitis (1).
Crimi 1995	No placebo arm in study. Comparison was between nedocromil sodium and theophylline.
Cusack 1986	No placebo arm in study.
Di Lorenzo 1998	There is no control group, only salmeterol and theophylline intervention groups.
Dini 2001	Not an RCT.
Dorow 1978	Allocation of treatment not randomised, although double‐blinding was used.
Dull 1981	This study presents data for post isoproterenol nebulisation response on the final day of 4‐wk placebo and theophylline period.
Evans 1984	Single dose study. Patients were given theophylline at 2200hrs on the eve of each study day and all patients were studies 12 hours later. Varying single doses were used (200, 400, 600 and 800 mg) on separate days.
Fitzpatrick 1992	The subjects included in this study are healthy volunteeers
Greening 1981	The population is not COPD. They have asthma.
Harkaway 1985	No placebo arm, study comparing 2 preparations of theophylline.
Horiguchi 1999	Not COPD but study done in patients with asthma.
Hudson 1973	No placebo arm in study.
Javaheri 1996	The population studied in this paper have heart failure not COPD
Karpel 1994	There are four grops in this study : ipratropium + theophylline + albuterol vs theophylline + albuterol vs ipratropium vs placebo. But there are no theophylline only group.
Lamont 1982	Study included patients with greater than 20% reversibility in FEV1 after beta2 agonists from pMDI, therefore COPD patients only not included in study.
Lefcoe 1982	Because of the distribution of the grous: P = placebos (2 oral, plus one aerosol), F + T = fenoterol + teophylline, I = Ipratropium bromide + placebo + theophylline, F+ T + I = fenoterol+ theophylline + ipratropium bromide. So, there is not a isolated theophylline study group.
Leitch 1981	Single dose study lasting 3 hours.
Leuenberger 1997	Not an RCT but a review paper.
Lunell 1983	No placebo arm in study.
Mahon 1999	This was not a conventional RCT but an N of 1 trial, therefore it was excluded as only conventional RCT's were included. Patients in this study switched (crossover) to the "other" blinded treatment arm if the first treatment did not appear to work.
Man 1996	No placebo arm in study.
Marlin 1978	Not COPD patients.
Martin 1992	No placebo group in study.
McHardy 1981	Study specifically looked at chronic bronchitis patients only but also included some patients who had COPD. But the data for COPD patients is not presented separately but mentioned in text.
Melani 1994	There is no placebo group in this study.
Melillo 1989	There is no control group.
Morandini 1989	No placebo arm in study.
Oren 1997	This study is not randomised.
Poukkula 1989	Not patients with COPD.
Pulido 1989	Bamyphylline is a theophylline derivate. Our protocol includes only aminophylline and theophylline not their derivates.
Sacco 1995	In this study there was no placebo group. It was doxofylline versus theophylline groups.
Shivaram 1997	Single dose study lasting 120 minutes.
Siemon 1991	Study comparing two different theophylline preparations.
Steen 1980	No placebo arm in study. Tedral versus theophylline only.
Sutton 1981	Not COPD patients.
Svedmyr 1982	Single dose study in patients with asthma. Oral theophylline used in combination with terbutaline.
Taccola 1999	No placebo arm.
Tanzj 1974	Two different theophylline preparations compared with no placebo arm in study.
Tatsis 1988	This study does not a placebo group and includes bronchial asthmatics patients
Taylor 1985	Not COPD patients, mean bronchodilator reversibility in FEV1 of > 26%.
Tsukino 1998	Single dose study.
Umut 1992	Not an RCT.
Van Andel 1999	Not a RCT.
Vereen 1986	Use of iv aminophylline preparation.
Villani 1997	Because doxophylline is a theophylline derivate. Our protocol includes only aminophylline and theophylline.
Vyse 1989	No placebo group.
Wiessmann 1975	Allocation of treatment not randomised, although double‐blinding was used.
Winter 1984	No placebo arm. Study only included a comparison between theophylline versus salbutamol.
Yang 2001	Not COPD patients but asthma.
ZuWallack 2001	Study was primarily comparing theophylline plus salmeterol as a combination treatment. Although the study had theophylline only arm it did not have a placebo only arm so the study cannot be included in the review.