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L J Dowson

Publications and source records attributed to L J Dowson.

7 recordsLinked to original sources
PubMed2003

Predictors of mortality in alpha1-antitrypsin deficiency.

BACKGROUND: Lung density measurements by computed tomography have previously been found to be a more sensitive indicator of disease progression in emphysema of alpha(1)-antitrypsin deficiency than lung function measurements. The aim of this study was to investigate the predictive potential of several parameters, including CT scanning, for mortality in patients with severe alpha(1)-antitrypsin deficiency. METHODS: Over a 5 year period, 256 patients with alpha(1)-antitrypsin deficiency (PiZ phenotype) were assessed, of whom 254 underwent lung function testing and 197 had thoracic CT scans. Lung function, CT scans, health status (St George's Respiratory Questionnaire, SGRQ), and other clinical data of survivors and non-survivors were compared and these parameters were applied to survival analyses. RESULTS: There were 22 deaths in this patient cohort, 10 of which were classified as "respiratory" deaths. Baseline lung function parameters (forced expiratory volume in 1 second (FEV(1)), carbon monoxide transfer coefficient (KCO)), and CT scores were significantly lower in the non-survivors than in the survivors. 170 of the 256 patients had complete data for entry into multiple regression analyses (Cox proportional hazards model). In the univariate analysis, upper zone expiratory scan had the best association with all cause (p = 0.001) and respiratory mortality (p<0.001), whereas FEV(1) (p = 0.158 all cause, 0.015 respiratory) and KCO (p = 0.002 all cause, 0.012 respiratory) had poorer associations with mortality. Only age gave further independent predictive information regarding all cause or respiratory mortality when the CT scan was entered into the survival analyses. CONCLUSIONS: CT scanning predicts respiratory and all cause mortality in alpha(1)-antitrypsin deficiency and appears to be superior to lung function parameters, especially FEV(1).

Disease Progression↗
PubMed2001

Longitudinal changes in physiological, radiological, and health status measurements in alpha(1)-antitrypsin deficiency and factors associated with decline.

The FEV(1) declines rapidly in alpha(1)-antitrypsin deficiency (alpha(1)-ATD) but less is known about other measures of disease severity and the factors, other than smoking, that are associated with progression of emphysema. The natural history of alpha(1)-ATD was studied prospectively in 43 patients with the PiZ phenotype and emphysema at a single center over 2 yr. The mean +/- SE change in FEV(1) was -67 +/- 14 ml/yr, accompanied by a reduction in transfer factor (mean change in diffusing capacity of the lung for CO [DL(CO)] -1.07 +/- 0.21 ml/min/mm Hg/yr; p < 0.001) and lung density in the upper zones as assessed by quantitative high-resolution computed tomography (HRCT) (mean change in voxel index 2.8 +/- 0.6%/yr; p < 0.001). The decline in FEV(1) related to baseline FEV(1) (r = -0.56, p < 0.001), bronchodilator reversibility (r = 0.52, p < 0.001), and (for patients with FEV(1) > 35% predicted) exacerbation frequency (r = -0.38, p = 0.02). There was also a decline in the St. George's Respiratory Questionnaire (SGRQ) Activity score (mean change -4.3 +/- 1.2 units/yr, p < 0.001) that correlated with FEV(1) decline (r = 0.45, p = 0.002). Progression of emphysema in alpha(1)-ATD is dependent on baseline physiology and exacerbation frequency and may be detected by several different measurements of which HRCT density mask analysis and DL(CO) appear most sensitive.

Adult↗
PubMed2001

Exercise capacity predicts health status in alpha(1)-antitrypsin deficiency.

Resting lung function is only weakly related to health status in chronic obstructive pulmonary disease, reflecting the multifactorial causes of impairment and the heterogeneous nature of the condition. The current study examined whether density mask analysis of high-resolution computed tomography (HRCT) or exercise capacity were better surrogates for health status in a well-defined, homogeneous group of patients with alpha(1)-antitrypsin deficiency (PiZ). Twenty-nine patients with predominantly lower zone emphysema on HRCT were studied. Exercise was assessed by incremental treadmill (V O(2) peak) and shuttle walking tests (ISWT) and health status by the St. George's Respiratory Questionnaire (SGRQ) and SF-36. Although lower zone expiratory HRCT was related to exercise capacity (rho = -0.64 and -0.63 for V O(2) peak and ISWT, respectively, p < 0.001), multiple regression analysis suggested that FEV(1) was a marginally better predictor (rho = -0.64 and -0.65, p < 0.001). HRCT also related significantly to health status (rho = -0.37 for SGRQ activity, p < 0.05), although again FEV(1) showed a stronger relationship (rho = -0.43, p = 0.01). However, exercise capacity was the best predictor of health status with the ISWT accounting for up to 55% of the variability seen in SGRQ total and up to 53% of the SF-36 domain scores (physical functioning). Although both HRCT and lung function relate to health status, exercise capacity is the best predictor of patients disability in these patients with predominantly lower zone emphysema.

Exercise Test↗
PubMed2001

High-resolution computed tomography scanning in alpha1-antitrypsin deficiency: relationship to lung function and health status.

The development of computed tomography (CT) has enabled emphysema to be assessed noninvasively. Objective quantification of lung density correlates well with lung function in patients with chronic obstructive pulmonary disease and has been shown to be a sensitive tool for monitoring disease progression. In order to determine the clinical impact of changes seen on high-resolution computed tomography (HRCT), the relationship between the objective quantification of emphysema on HRCT, lung function and health status in 111 patients with alpha1-antitrypsin deficiency was examined (PiZ). The degree of HRCT scan abnormality correlated well (p<0.001 for all comparisons) with forced expiratory volume in one second (r = -0.60- -0.75), specific airway conductance (r = -0.67-0.76), residual volume/total lung capacity (r = 0.46-0.58) and transfer factor of the lung for carbon monoxide (r = -0.64- -0.81). In addition, the CT scans correlated (p<0.001) with health status as assessed by the St. George's Respiratory Questionnaire (SGRQ total: r = -0.38-0.50) and the Short-Form health survey (e.g. physical functioning: r = -0.39-0.54). In summary, other workers have shown high-resolution computed tomography to be a sensitive indicator of disease progression. This study confirms the relationship between high-resolution computed tomography and lung physiology, and suggests the relationship is even stronger in patients with predominantly lower zone pan-lobular emphysema than in usual chronic obstructive pulmonary disease. High-resolution computed tomography also relates to patients disability and impairment as defined by health status questionnaires and, therefore, should be considered as an alternative outcome measure particularly in alpha1-antitrypsin deficiency.

Adult↗
PubMed1999

General practice spirometry in North Staffordshire.

Spirometry is suggested, in North American and European guidelines, to be the most important measurement of lung function for the management of patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to determine attitudes to and utilization of spirometry in general practices within North Staffordshire. All 95 practices in North Staffordshire were surveyed by telephone, using a standard proforma. Eighty-four practices (48 fundholding) containing 224 general practitioners (GPs) and serving 472,420 patients, agreed to take part. The survey was completed by practice nurses on 63 occasions, GPs on 14 and practice managers on seven. Eighteen practices possessed a spirometer, although eight did not use it. The measurements were performed by doctors in five of the practices, nurses in two and by both in three. Only two users had received formal training in the performance and interpretation of spirometry. Of the three practices using pneumotachograph spirometers, none knew how often the machine should be calibrated. Spirometry was used by five practices for diagnosis (although only four used it to determine forced expiratory volume in one second (FEV1)), three for monitoring and only one for bronchodilator reversibility testing. Although 44 (52%) practices thought that, ideally, spirometry should be available in the practice, only 10 of the 18 who had spirometers were currently providing this facility. Furthermore, the poor training puts into question the validity of some of the results obtained. Open access to hospital spirometry is one method of addressing these problems, and 73 (87%) practices, including 16 who already owned a spirometer, said that they would use such a service.

Data Collection↗
PubMed1998

A re-audit of pulmonary function laboratories in the West Midlands.

In 1991 the West Midlands Pulmonary Function Audit Group examined the consistency between pulmonary function laboratories in the West Midlands. Three healthy subjects visited 22 centres and performed a standard set of pulmonary function tests. Demographic data on nine hypothetical subjects was also supplied for the laboratories to produce predicted values. Equipment was checked for accuracy using standard methods. The 1991 audit revealed significant inter-laboratory variability. Sources of error were identified and after consultation, recommendations were made to improve consistency. In addition, national and regional training workshops were organized for laboratory staff. In 1995 the audit was repeated using the same three subjects. Significant differences continued for all predicted results except for residual volume (RV) and forced vital capacity (FVC) and for all measured results except for functional residual capacity (FRC). However, improvements in the coefficient of variation were seen compared with 1991 for predicted forced expiratory volume (FEV1), total lung capacity (TLC), gas transfer (TLCO), FVC, FRC and RV. Similar improvements were seen in measured results for FEV1 and FVC. Increased variation was seen for predicted corrected transfer factor (KCO) and actual RV. The majority of variables in the 1995 audit had a coefficient of variation of less than 5% between laboratories. Analysis of the predicted results from the hypothetical subjects continued to show unacceptable variation reflecting continuing computer algorithm inconsistency. The improvements seen are encouraging and suggest that a regular audit programme is worthwhile.

Adult↗