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Biomedical subjects

J MacMahon

Publications and source records attributed to J MacMahon.

At least 19 recordsLinked to original sources
PubMed2005

Short burst oxygen therapy in chronic obstructive pulmonary disease: a patient survey and cost analysis.

The prescription of home oxygen cylinders is substantial. This study aimed to establish patient's current use of short burst oxygen therapy in chronic obstructive pulmonary disease (COPD) and to examine potential cost savings if cylinder use had been replaced by a concentrator. An interviewer-administered questionnaire was completed by 100 patients currently receiving short burst oxygen therapy. Patients reported that they used their oxygen before exercise/activity (26%), during exercise (19%), after exercise/activity (87%) and at rest (46%) and mostly for the relief of symptomatic breathlessness. The length of time [mean (SD)] patients had oxygen at home was 27.42 (29.31) months. Of those patients using cylinders, savings could have been made by transferring from cylinders to concentrators. While withdrawal of oxygen may be difficult, an oxygen assessment service could ensure that future prescription is aimed at those who benefit and is delivered by the most cost-effective method.

Aged↗
PubMed2004

Oesophageal pH monitoring is of limited value in the diagnosis of "reflux-cough".

Reflux-cough is a diagnosis based on demonstrating both gastro-oesophageal reflux and a positive response to anti-reflux therapy. The authors sought to determine early and long-term response to therapy in patients with a "positive" 24 h oesophageal pH study, and identify any features which might predict response. Patients with chronic cough were recruited from July 1998 to July 2002. Those with a positive pH study were given dietary advice and an 8-week trial of omeprazole (20 mg b.i.d.). Response was judged after 8 weeks (clinical follow-up), and at long-term follow-up (telephone questionnaire). A total of 146 patients underwent pH monitoring with 82 (56.2%) "positive" studies. Follow-up data was available in 60 patients, with 49 receiving anti-reflux therapy, of which 20 (40.8%) reported a positive treatment response. At long-term follow-up (median 30 months), there was a significantly lower response (14 out of 49, 28.5%), with no significant difference in either acid exposure times (distal/proximal) or symptom correlation between responders and nonresponders at early or long-term follow-up. In conclusion, despite "positive" pH studies, over half of the patients (55.1%) failed to respond to therapy. No features on pH monitoring accurately predicted response. Short-term response did not predict long-term response. The precise role for pH monitoring in the assessment of chronic cough remains to be defined.

Anti-Ulcer Agents↗
PubMed2004

Prescribing practice for intermittent oxygen therapy: a GP survey.

INTRODUCTION: UK figures show that the prescription of home oxygen cylinders for intermittent use is substantial. AIM: To examine GP assessment criteria and prescribing practice for intermittent oxygen therapy in patients with a diagnosis of chronic obstructive pulmonary disease (COPD) in Northern Ireland. METHODS: A postal questionnaire was sent to all GPs (n = 534) in two health boards who had prescribed cylinder oxygen in a six month period prior to the study. The questionnaire was piloted to establish reliability and validity. RESULTS: Completed questionnaires were returned by 52% (280/534) of GPs. GPs 'most frequently' used advice from hospital specialists [82% (230/280)] to determine the need for intermittent oxygen. Criteria such as breathlessness score on exercise (e.g., BORG), oximetry on exercise, local guidelines or national guidelines were used less frequently or never. CONCLUSIONS: Most patients are likely to have been prescribed intermittent oxygen without any objective assessment. Implementation of evidence-based guidelines and a formal oxygen assessment service, would rationalize the use of intermittent oxygen therapy and enable better targeting of this expensive resource.

Follow-Up Studies↗
PubMed2003

Smoking, atopy and certain furry pets are major determinants of respiratory symptoms in children: the International Study of Asthma and Allergies in Childhood Study (Ireland).

BACKGROUND: Environmental, cultural and health care differences may account for variation among countries in the prevalence of asthma and respiratory symptoms in teenagers. OBJECTIVE: To examine the prevalence of respiratory symptoms and the level of diagnosis, and to compare determinants of asthma and severe wheeze in two countries. METHODS: Self-completion questionnaires based on the International Study of Asthma and Allergies in Childhood (ISAAC) protocol were provided to school children in Ireland (Republic and Northern Ireland). In the Republic of Ireland, all children in classes largely aged 13-14 years from 30 post-primary schools were selected by random sampling stratified by school size, composition and Health Board in Spring 1995. In Northern Ireland, all children largely aged 13-14 years of age from 26 post-primary schools were selected by random sampling stratified by school type, composition and Education and Library Board in Spring 1996. RESULTS: Questionnaires were completed by 2,364 children from Northern Ireland and 2,671 from the Republic, about 90% of those eligible to participate. The prevalences of wheeze at various levels of severity, of diagnosed asthma and of treated wheeze were very similar in Northern Ireland and the Republic of Ireland. A significant proportion of those reporting more severe symptomatology (four or more attacks of wheeze in the past 12 months and/or one or more nights disturbed and/or moderate or greater disruption of daily activities and/or speech restriction due to wheeze) had been neither diagnosed nor treated for asthma (20-37%). To investigate the determinants of the more severe symptomatology of asthma or treated wheeze a series of stepwise multiple regression analyses was performed. A history of atopy, cigarette smoking, the possession of a furry pet other than a dog or cat and age were each independently associated with severe wheeze, whilst atopy, a furry pet (as above) and gender were each independently associated with asthma or treated wheeze. CONCLUSIONS: Cigarette smoking is closely associated with the reporting of significant respiratory symptoms together with atopy and exposure to furry pets. Some 20-37% of severe symptoms were neither diagnosed nor treated as asthma.

Adolescent↗
PubMed2003

Lung cancer survival in Northern Ireland.

Lung cancer causes more deaths than any other cancer in Northern Ireland. Survival, and factors which could influence survival, were examined for the 4,458 patients diagnosed with lung cancer from 1992 to 1996. Overall five-year relative survival was low, but better for females (9%) than males (7%). Survival improved each year although this could not be attributed to treatment changes. Survival was better for men under 65 years, than older men (p<0.01), while survival from non-small cell type lung cancer was better than small cell (p<0.001). The proportion of patients having bronchoscopy and CT scan increased over the study period. Although the proportion of patients receiving surgery or radiotherapy remained unchanged over the period there was an increase in the proportion receiving chemotherapy (8.7% vs. 9.4%, P<0.05). Survival rates, although slightly better than in the rest of the United Kingdom, were poorer than in several other countries, including the Republic of Ireland and the United States of America. High mortality rates from lung cancer and, at best, modest improvements in survival, point to the need for increased efforts to reduce levels of lung cancer by tackling the main cause, smoking.

Age Distribution↗
PubMed2001

Sleep complaints and risk factors for excessive daytime sleepiness in adult males in Northern Ireland.

The prevalence of sleep complaints in Northern Ireland is unknown. Sleep disruption can result in excessive daytime sleepiness (EDS), with significant socioeconomic consequences. The aim of this study was to assess the prevalence of sleep complaints and to determine risk factors for EDS in a Northern Irish community. From an urban and rural community of 499,111 people, a random sample of 3391 adult men were sent a questionnaire by mail. Questions were asked regarding sleep, EDS and medical history. There were 2364 completed questionnaires returned (response rate 70%). The mean age of respondents was 46.0 years (range 18--91 years). 26.7% of men were not satisfied with their usual night's sleep and 68% of men woke up at least once during the night. Based on pre-defined criteria, 24.6% of the population had insomnia and 19.8% had EDS. The strongest risk factor identified for EDS was a history of snoring loudly (odds ratio 2.62; 95% CI 1.82--3.77). Other risk factors included ankle swelling, feeling sad or depressed stopping sleep, experiencing vivid dreams while falling asleep, waking up feeling unrefreshed and age > 35 years. The prevalence rates of sleep complaints and EDS in this community-based study is high, although this does depend directly on the criteria used to define insomnia and EDS. Recognition of risk factors for EDS may help to identify and treat those affected.

Adolescent↗
PubMed2000

Sensory neuropeptides induce histamine release from bronchoalveolar lavage cells in both nonasthmatic coughers and cough variant asthmatics.

BACKGROUND: Sensory neuropeptides have been suggested to play a role in the pathogenesis of a number of respiratory diseases including asthma and chronic non-productive cough. OBJECTIVES: To investigate the action of sensory neuropeptides on airway mast cells obtained by bronchoalveolar lavage (BAL). METHODS: BAL was performed on 23 nonasthmatic patients with cough (NAC), 11 patients with cough variant asthma (CVA) and 10 nonatopic controls. Washed lavage cells were stimulated (20 min, 37 degrees C) with calcitonin gene-related peptide (CGRP), neurokinin A (NKA) and substance P (25 and 50 micromol/L). RESULTS: The neuropeptides tested induced histamine release in all groups studied. Only CGRP (50 micromol/L) induced significantly more histamine release from both NAC and CVA patients compared with control subjects (P = 0.038 and 0.045, respectively). CONCLUSION: Regardless of aetiology, mast cells from patients with chronic cough appear to have an increased responsiveness to CGRP compared with controls. The results of the present study suggest that the role of CGRP in chronic cough should be further investigated.

Adolescent↗
PubMed2000

Is there an association between angiotensin-converting enzyme gene variants and chronic nonproductive cough?

BACKGROUND: It is unclear why some patients develop a chronic nonproductive cough. Angiotensin-converting enzyme (ACE) inactivates tussive peptides in the airways such as bradykinin and tachykinins. An insertion/deletion polymorphism in the ACE gene accounts for variation in ACE levels, and patients with the II genotype have lowest serum ACE levels compared with ID and DD genotypes. We hypothesized that the II genotype would be associated with increased risk of developing a chronic cough. MATERIALS AND METHODS: We recruited 47 patients (33 women), referred for evaluation of cough (median cough duration, 24 months; range, 2 to 240 months). Cough patients were evaluated using a comprehensive diagnostic protocol, and cough reflex sensitivity was measured using a capsaicin inhalation challenge. ACE genotyping was performed on DNA samples from patients using the polymerase chain reaction followed by agarose gel electrophoresis. ACE genotypes in patients with chronic cough were compared with those in 199 healthy control subjects. Serum ACE levels were determined using a colorimetric assay. RESULTS: Genotype frequencies for the ACE gene were similar between patients and control subjects. There was no correlation between capsaicin sensitivity and ACE genotypes or serum ACE levels. CONCLUSION: Susceptibility to develop chronic cough is not associated with ACE genotype.

Adolescent↗
PubMed1999

Cost minimisation analysis of provision of oxygen at home: are the drug tariff guidelines cost effective?

OBJECTIVES: To determine the level of oxygen cylinder use at which it becomes more cost effective to provide oxygen by concentrator at home in Northern Ireland, and to examine potential cost savings if cylinder use above this level had been replaced by concentrator in 1996. DESIGN: Cost minimisation analysis. SETTING: Area health boards in Northern Ireland. MAIN OUTCOME MEASURES: Cost effective cut off point for switch to provision of oxygen from cylinder to concentrator. Potential maximum and minimum savings in Northern Ireland (sensitivity analysis) owing to switch to more cost effective strategy on the basis of provision of cylinders in 1996. RESULTS: In Northern Ireland it is currently cost effective to provide oxygen by concentrator when the patient is using three or more cylinders per month independent of the duration of the prescription. More widespread use of concentrators at this level of provision is likely to lead to a cost saving. CONCLUSIONS: The Drug Tariff prescribing guidelines, advocating that provision of oxygen by concentrator becomes cheaper when 21 cylinders are being used per month-are currently inaccurate in Northern Ireland. Regional health authorities should review their current arrangements for provision of oxygen at home and perform a cost analysis to determine at what level it becomes more cost effective to provide oxygen by concentrator.

Cost Savings↗
PubMed1999

Bronchoalveolar lavage findings in patients with chronic nonproductive cough.

Mast cells and eosinophils may play a role in the pathophysiology of chronic cough in nonasthmatics. It is unknown, however, whether degranulation of these cells occurs in the airways of such patients. Thirty-five nonsmoking patients referred with a chronic nonproductive cough (mean cough duration 76.2 months) were evaluated using a comprehensive diagnostic protocol. Bronchoalveolar lavage (BAL) cell differentials and BAL histamine, tryptase and eosinophilic cationic protein (ECP) concentrations were determined. Ten nonsmoking healthy volunteers served as controls. Diagnostic subgroups were identified: eight postnasal drip syndrome (PNDS), seven cough variant asthma (CVA), seven gastro-esophageal reflux (GOR), seven dual aetiology and six idiopathic. Nonasthmatic coughers (NAC) were characterized as those patients without bronchial hyperresponsiveness on histamine challenge and whose cough had either responded to therapy for PNDS or GOR or failed to improve with antiasthma therapy. There was a significant increase in both eosinophil and mast cell numbers (p<0.05) and in histamine levels (p = 0.027) when NAC patients were compared with controls. Tryptase and ECP levels were elevated in 7 of 23 and 6 of 23 NAC patients, respectively. In conclusion, airway inflammatory cell numbers are not only increased but also activated, suggesting an important role for airways inflammation in the pathophysiology of chronic nonproductive cough.

Adult↗
PubMed1999

Adenosine induces histamine release from human bronchoalveolar lavage mast cells.

Previous studies have shown that in vitro adenosine enhances histamine release from activated human lung mast cells obtained by enzymic dispersion of lung parenchyma. However, adenosine alone has no effect on histamine release from these cells. Given the evidence for direct activation of mast cells after endobronchial challenge with adenosine and previous studies indicating that mast cells obtained at bronchoalveolar lavage are a better model for asthma studies than those obtained by enzymic dispersion of lung tissue, the histamine-releasing effect of adenosine was examined on lavage mast cells. Bronchoalveolar lavage fluid was obtained from patients attending hospital for routine bronchoscopy (n=54). Lavage cells were challenged with adenosine or adenosine receptor agonists (20 min, 37 degrees C) and histamine release determined using an automated fluorometric assay. Endogenous adenosine levels were also measured in lavage fluid (n=9) via an HPLC method. Adenosine alone caused histamine release from lavage mast cells in 37 of 54 patients with a maximal histamine release of 20.56+/-2.52% (range 5.2-61%). The adenosine receptor agonists (R)-N6-(2-phenylisopropyl)adenosine, 5'-N-ethylcarboxamidoadenosine and CGS21680 also induced histamine release from lavage mast cells. Preincubation of lavage mast cells with the adenosine receptor antagonist xanthine amine congener caused significant inhibition of the response to adenosine (P=0.007). There was an inverse correlation between endogenous adenosine levels in the lavage fluid and the maximal response to in vitro adenosine challenge of the lavage cells. The findings of the present study indicate a means by which adenosine challenge of the airways can induce bronchoconstriction and support a role for adenosine in the pathophysiology of asthma. The results also suggest that cells obtained from bronchoalveolar lavage fluid may provide the ideal model for the testing of novel, adenosine receptor, targeted therapies for asthma.

Adenosine↗
PubMed1998

Evaluation and outcome of patients with chronic non-productive cough using a comprehensive diagnostic protocol.

BACKGROUND: Asthma, post-nasal drip syndrome (PNDS), and gastro-oesophageal reflux (GOR) account for many cases of chronic non-productive cough (CNPC). Each may simultaneously contribute to cough even when clinically silent, and failure to recognise their contribution may lead to unsuccessful treatment. METHODS: Patients (all lifetime non-smokers with normal chest radiographs and spirometric measurements) referred with CNPC persisting for more than three weeks as their sole respiratory symptom underwent histamine challenge, home peak flow measurements, ear, nose and throat (ENT) examination, sinus CT scanning, and 24 hour oesophageal pH monitoring. Treatment was prescribed on the basis of diagnoses informed by investigation results. RESULTS: Forty three patients (29 women) of mean age 47.5 years (range 18-77) and mean cough duration 67 months (range 2-240) were evaluated. On the basis of a successful response to treatment, a cause for the cough was identified in 35 patients (82%) as follows: cough variant asthma (CVA) (10 cases), PNDS (9 cases), GOR (8 cases), and dual aetiologies (8 cases). Histamine challenge correctly predicted CVA in 15 of 17 (88%) positive tests. ENT examination and sinus CT scans each had low positive predictive values for PNDS (10 of 16 (63%) and 12 of 18 (67%) positive cases, respectively), suggesting that upper airways disease frequently co-exists but does not always contribute to cough. When negative, histamine challenge and 24 hour oesophageal pH monitoring effectively ruled out CVA and GOR, respectively, as a cause for cough. CONCLUSION: This comprehensive approach aids the accurate direction of treatment and, while CVA, PNDS and GOR remain the most important causes of CNPC to consider, a group with no identifiable aetiology remains.

Adolescent↗
PubMed1997

Brewer's asthma due to malt contamination.

We describe a case of a 28 year old brewery worker who developed asthma whilst grinding malt. Lung function measurements demonstrated deterioration and improvement in lung function associated with work and absence from work. Inhalation challenge with ground malt from the brewery was positive but with ground malt from another source was negative suggesting a contaminant of the malt was responsible. Culture of the brewery malt showed heavy contamination with Aspergillus niger, but A. niger skin test was negative and aspergillus-specific IgG was not detected in the patients serum. Removal of the subject from the grinding room resulted in resolution of symptoms and normal lung function. We discuss the role of A. niger as an aetiological agent for occupational asthma with reference to the above case.

Adult↗
PubMed1997

Prescription of oxygen concentrators and survival in Northern Ireland.

Long-term oxygen therapy (LTOT) has been shown to prolong survival and to improve quality of life in patients with chronic obstructive pulmonary disease (COPD) and in respiratory failure. In Northern Ireland oxygen concentrators have been available on prescription since August 1986, initially on a restricted basis from hospital physicians only. This was followed by open prescribing from April 1989, when concentrators could be prescribed by general practitioners. This study examined prescribing habits of LTOT during both periods, and patient survival. Case notes of all prescriptions of oxygen concentrators in Northern Ireland (to April 1991) were reviewed. Prescription criteria and advice regarding usage during both periods were analysed. A questionnaire survey of subjects during open prescribing documented the advice given at the time of prescription and current usage. 164 charts of 178 total installations were available for review. During both periods many concentrators were installed without adherence to the prescribing criteria at the time (75% restricted, 48% open). The majority of these were on the advice of a consultant respiratory physician and only 14 were prescribed directly by GPs. 89 of 91 subjects receiving current LTOT during the study period completed questionnaires. Of the subjects prescribed LTOT during the restricted period, 2 subjects are still alive (median survival 19 m, range 0-104). From the open period, survival data was available on 107 of 129 subjects with 17 still alive (median survival 22 m, range 0-94). This study documents an inadequate rate of prescribing and a lack of conformity to guidelines in the provision of LTOT in Northern Ireland. We would suggest that familiarisation with the prescribing criteria, formal written advice at the time of prescription, appropriate follow up to ensure adequate supplementation and regular patient education on the use of LTOT would address these problems to a substantial degree.

Aged↗