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Biomedical subjects

David L Hahn

Publications and source records attributed to David L Hahn.

11 recordsLinked to original sources
PubMed2006

Secondary outcomes of a pilot randomized trial of azithromycin treatment for asthma.

OBJECTIVES: The respiratory pathogen Chlamydia pneumoniae (C. pneumoniae) produces acute and chronic lung infections and is associated with asthma. Evidence for effectiveness of antichlamydial antibiotics in asthma is limited. The primary objective of this pilot study was to investigate the feasibility of performing an asthma clinical trial in practice settings where most asthma is encountered and managed. The secondary objectives were to investigate (1) whether azithromycin treatment would affect any asthma outcomes and (2) whether C. pneumoniae serology would be related to outcomes. This report presents the secondary results. DESIGN: Randomized, placebo-controlled, blinded (participants, physicians, study personnel, data analysts), allocation-concealed parallel group clinical trial. SETTING: Community-based health-care settings located in four states and one Canadian province. PARTICIPANTS: Adults with stable, persistent asthma. INTERVENTIONS: Azithromycin (six weekly doses) or identical matching placebo, plus usual community care. OUTCOME MEASURES: Juniper Asthma Quality of Life Questionnaire (Juniper AQLQ), symptom, and medication changes from baseline (pretreatment) to 3 mo posttreatment (follow-up); C. pneumoniae IgG and IgA antibodies at baseline and follow-up. RESULTS: Juniper AQLQ improved by 0.25 (95% confidence interval; -0.3, 0.8) units, overall asthma symptoms improved by 0.68 (0.1, 1.3) units, and rescue inhaler use decreased by 0.59 (-0.5, 1.6) daily administrations in azithromycin-treated compared to placebo-treated participants. Baseline IgA antibodies were positively associated with worsening overall asthma symptoms at follow-up (p = 0.04), but IgG was not (p = 0.63). Overall asthma symptom improvement attributable to azithromycin was 28% in high IgA participants versus 12% in low IgA participants (p for interaction = 0.27). CONCLUSIONS: Azithromycin did not improve Juniper AQLQ but appeared to improve overall asthma symptoms. Larger community-based trials of antichlamydial antibiotics for asthma are warranted.

Journal Article↗
PubMed2002

Chlamydia pneumoniae as a respiratory pathogen.

Chlamydia pneumoniae is a recently recognized human respiratory pathogen with a unique biphasic life cycle characterized by an obligate intracellular (replicative) and an extracellular (infectious) form of the organism. C. pneumoniae is widely distributed and, via the respiratory route, infects the majority of the world's population. The majority (70%) of acute human C. pneumoniae respiratory tract infections are asymptomatic or only mildly symptomatic but a minority (30%) cause more severe respiratory illnesses including community-acquired pneumonia, bronchitis and a variety of upper airway illnesses. After acute infection the C. pneumoniae intracellular life cycle is characterized by the development of metabolically inert (and thus antibiotic resistant) atypical "persistent" inclusions; this biologic behavior correlates with a clinical course following acute symptomatic illness that is characterized by persistence of symptoms that are difficult to treat with antibiotics. A role for C. pneumoniae in chronic respiratory illness is currently under investigation: "persistent" intracellular inclusions contain increased quantities of chlamydial heat shock protein 60 (hsp 60), a highly immunogenic protein that has been implicated in the pathogenesis of established chronic inflammatory chlamydial diseases (blinding trachoma, pelvic inflammatory disease and tubal infertility). An emerging body of evidence, including host immune response to chlamydial hsp 60, links C. pneumoniae infection with a spectrum of chronic inflammatory lung diseases of currently unknown etiology (asthma, chronic bronchitis and chronic obstructive pulmonary disease (COPD)). Further laboratory developments, including reliable and practical diagnostic methods and antibiotics effective against persistent infection, will be required to recognize and treat acute C. pneumoniae infection, and to advance our knowledge and understanding of the role of chronic infection in asthma, chronic bronchitis and COPD.

Acute Disease↗
PubMedDate not supplied

Feasibility of a practical clinical trial for asthma conducted in primary care.

BACKGROUND: Practical clinical trials (PCTs) are essential to generate relevant evidence-based information to improve patient health. Primary care physicians' experience performing randomized controlled trials (RCTs) on representative patient populations is limited. We implemented a pilot practice-based asthma PCT to answer the following feasibility questions: (1) Was clinician interest initiated and maintained? (2) Did clinicians enroll patients into an RCT and complete follow-up? (3) Was an interactive voice-response (IVR) telephone system useful to collect patient-reported data? METHODS: The protocol included (1) broadly representative adult asthma eligibility criteria, (2) self-reported patient-oriented outcomes, and (3) use of IVR to collect these data. Physicians in practice-based research networks, managed care organizations, and academic networks volunteered to participate. RESULTS: Of 13 physician volunteers, 10 (8 single-person office practices, 1 emergency department physician, 1 clinical researcher) from 4 states and 1 Canadian province enrolled 58 subjects and randomized 45 meeting final eligibility criteria; 39 (87%) attended the follow-up visit. However, only 34 (76%) provided adequate follow-up IVR self-report data, and subjects with less than a high school education provided significantly (P <.001) less data than other groups. CONCLUSIONS: Physician recruiting, randomizing, and completing a representative sample of adult asthma patients was feasible. The utility of IVR in primary care research requires further study.

Adult↗