This week the American Academy of Allergy, Asthma and Immunology has published a report on air filters and air cleaners that should help answer that question. The entire report is available free via PubMed.

Actually it goes well beyond that, with a thorough review of air filtration, the characteristics of airborne particulates – including allergens and particulate matter – and the range of available filter/cleaning strategies and technologies, from portable room air cleaners, to HVAC and powered electric filters.

One of the more interesting conclusions of the report is that air cleaning and filtration be viewed as a strategy for minimizing disease progression rather than as a treatment. As the report puts it, “It is not logical to expect that the observed disease state symptoms, often the result of previous prolonged exposures either in the home, other environments, or both, will abate within a few weeks or even months after the placement of an air-cleaning device or filter in the home environment. Other factors, especially source control and ventilation, might play a more important role than attempts to clean the air after the fact by means of filtration.”

They recommend that more rigorous and lengthy trials are needed before definitive recommendations on the efficacy of air filtration in improving disease can be made. Obviously there is a big role in these studies for more robust baseline and prospective data on symptoms and symptom severity, medication use and various objective markers (lung function). But I really like their idea of blinding and placebo-controlling the studies.

The group concludes that, given the current evidence, use of effective air filtration does reduce indoor levels of ambient particulates, that “that might trigger disease processes themselves.”

What to use? “Portable room air cleaners with HEPA filters, especially those that filter the breathing zone during sleep, appear to be beneficial. For the millions of households with forced air HVAC systems, regular maintenance schedules and the use of high-efficiency disposable filters appear to be the best choices.”

Novel technology automatically tracks where and when attacks occur

Beginning next week, Madison-based Reciprocal Sciences, with funding from the US Centers for Disease Control and Prevention, will launch a new study to learn more about the problem of rural asthma in the Midwest. The study follows a recent report by the CDC that rates of asthma in rural areas have been underestimated.

“Our analyses of national survey data suggest that asthma is as prevalent in rural areas as in urban areas,” says Teresa Morrison, medical epidemiologist in the Air Pollution and Respiratory Health Branch at CDC. “Our goal is to document patterns of asthma symptoms among rural residents in Midwestern states, and learn more about possible environmental exposures that potentially lead to asthma attacks.”

In the past, studies have relied on interviews and questionnaires to collect data on asthma. But now, volunteers who live in rural areas in the Midwest will be able to record their symptoms when and where they happen, using an innovative tool that Reciprocal Sciences unveiled last year. The device, called the Spiroscout, is a GPS-enabled inhaler that pinpoints the exact geographic location and time when the inhaler is used.

“For the first time, scientists will have definitive information about exactly where and when rural residents have symptoms,” says study director David Van Sickle, PhD, “and we can use that to identify important patterns in the disease.”

Participants in the six-month study will also be testing additional asthma management tools developed by Reciprocal Sciences, including a text messaging system designed to help people with asthma remember to take their daily medication.

Participation in the study is limited to 150 participants. Interested individuals can call (608) 554-0750, email info@reciprocalsciences.com or visit the project website for more information.

Overall asthma control: The relationship between current control and future risk (E. Bateman et al. – JACI)

Very interesting retrospective analysis of five studies which examines the relationship between asthma control (assessed by questionnaire and guideline criteria) and the risk of future instability and exacerbations in asthma. Bateman and colleagues report that the percentage of patients achieving asthma control increased with time, irrespective of treatment, and not suprisingly, that asthma control score at baseline associated with exacerbation rates. In addition, the authors used Markov analysis to examine the transitional probability of change in control status throughout the studies. The finding: “A Controlled or Partly Controlled week predicted at least Partly Controlled asthma the following week (≥80% probability). The better the control, the lower the risk of an Uncontrolled week. The probability of an exacerbation was related to current state.”

Socioeconomic risk factors for lung function decline (Johannessen et al. – ERJ)

Interesting new report from a cohort study of more than 1,600 adults who performed spirometry in 1996-97 and again in 2003-6 that found gender-specific associations between different aspects of SES (socioeconomic status) and lung function decline. “Lower education and low occupational status were associated with larger male lung function decline…SES did not affect female lung function decline. However, marital status was a significant predictor; unmarried females had less decline than both married and widowed females” in both FEV1 and FVC.

Lessons learned from variation in response to therapy in clinical trials (Szefler and Martin – JACI )

“In the past, we viewed lack of response to asthma medications as a rare event. Based on recent studies, we now expect significant variation in treatment response for all asthma medications.” Szefler and Martin discuss how findings from multi-center asthma research networks (ACRN and CARE) are providing valuable new information about interindividual variability in response to a number of important controller medications. Using patient “characteristics, such as age and allergic status, and biomarkers, such as bronchodilator response, exhaled nitric oxide, and urinary leukotrienes,” can help physicians predict response and “personalize asthma treatment at the time of initiating long-term control therapy.”

Measuring asthma control: a comparison of three classification systems (O’Byrne et al. – ERJ)

In this paper, O’Byrne and colleagues compared three popular methods of assessing asthma control: The Asthma Control Questionnaire (ACQ-5) and two criteria based measures from the Global Initiative for Asthma (GINA) and Gaining Optimal Asthma ControL (GOAL) study. The review analyzed data from more than 8,000 subjects in three trials of the same asthma treatments. GINA and GOAL criteria provided similar assessments of asthma control, however, the ACQ-5 “detected clinically important improvements” in a large number of patients that according to other criteria remained uncontrolled. “ACQ-5 is more responsive to change in a clinical trial setting than a categorical scale.”

Social determinants of asthma [Cruz et al. - ERJ]
Editorial accompanying a report in ERJ by Sembajwe et al. on the relationship between gross national income, the prevalence of symptoms and doctor diagnosis of asthma. Cruz et al. review the interesting bimodal association between socioeconomic status and asthma and offer some thoughts on the puzzle, and the important distinction between risk of asthma ever and current symptoms: “Gross national product per capita is generally associated with both an increasing prevalence of wheezing ever and wheezing in the last 12 months. However, the prevalence of current symptoms is modifiable by current exposures (to allergens and environmental pollution,as well as other factors) and by effective treatment. Thus,even where prevalence is low, the burden of disease may be high, and poverty emerges as an important risk factor for current symptoms of asthma.”

What Genes Tell us about the Pathogenesis of Asthma and COPD [Weiss - AJRCCM]
“Recently a series of Genome Wide Association Study manuscripts (GWAS) in asthma and COPD have been published. These papers suggest that, in part, asthma and COPD have a common genetic origin, and that this common origin, is due to polymorphisms in genes that are involved with the development of the lung.”

Hygiene Hypothesis wanted: Dead or Alive [Linneberg letter and Douwes and Pearce reply - IJE]
This month IJE has published an interesting exchange between Allan Linneberg (http://bit.ly/9hunjr) and Douwes and Pearce (http://bit.ly/bd0Lz0), who suggest that “detailed exposure assessment strategies for both allergens and other potentially protective co-exposures are likely to shed new light on the roles of these exposures in the development of asthma and the validity of the hygiene and allergen tolerance hypotheses more generally.”

Follow up discussion to an editorial (PDF) published in 2008 by Jeroen Douwes and Neal Pearce, called, “The end of the hygiene hypothesis?” which concluded that “New aetiological theories of global asthma prevalence are, therefore, required that are more consistent with the epidemiological evidence and which take into account factors affecting the time trends for both allergic and non-allergic asthma.”

I had recently seen an article about the growing number of hospitals publishing their wait times online, but since that information is scattered across multiple sites, I found it a challenge to quickly compare and evaluate wait times in a given geographic area.

In addition, I found that there was no mechanism for people to independently report how long they waited to be seen by a physician.

As an experiment, I built ERwaittimes.us to aggregate current wait times published by hospitals nationwide and to provide a way for people to add their own wait times for every emergency room and urgent care. So far, it’s just a simple site that needs a lot more development. Please let me know what you think of the idea and how it could be improved.

Rapid reduction in hospitalizations after an intervention to manage severe asthma (ERJ – Souza-Machado et al.) – Evaluation of the Programme for Control of Asthma in Bahia (ProAR) which focused on providing free management of severe asthma. Achieved an 82% decline in asthma hospital admissions between 1998-2006, and report an “inverse correlation between provision of medication for asthma and hospitalization.”

Different definitions in childhood asthma: how dependable is the dependent variable? (ERJ – van Wonderen et al.) – Amazing review of 122 papers yielded 60 different definitions of asthma. “Prevalence estimates varied between 15.1% and 51.1% depending on the asthma definition used. The percentage of children whose posterior asthma probability was in the area of clinical indecision varied from 14.9% to 65.3%.” Conclusion – “Variation in definitions and its effect on the performance of prediction models may be another source of otherwise inexplicable variation in daily clinical decision making.”

Confirmation of Asthma in an Era of Overdiagnosis (ERJ – Luks et al.) – Following up on their recent report that 30% of adults with a physician diagnosis of asthma did not have asthma when objectively assessed, this article demonstrates that, “For the majority with a previous physician diagnosis of asthma only pre- and post- bronchodilator spirometry and a single methacholine challenge test are required to confirm asthma.”

Changes in the Prevalence of Asthma in Adults since 1966: The Busselton Health Study (ERJ – James et al.) – Cross-sectional respiratory health surveys of Busselton adults conducted in 1966, 1969, 1972, 1975, 1981, 1990 and in 2005-07 indicate that increased rates of doctor-diagnosed asthma are “partly explained by increased symptoms and atopy”; however, “factors such as diagnostic transfer and increased awareness of asthma have also contributed to the rise in prevalence.”

I humbly added my classroom epi project (EpiLab) to the mix. It’s a CDC-funded project to introduce high school students to epi and public health surveillance. Please have a look and share your thoughts to help me make it better – http://bit.ly/d3Xz3M

This bill – HR 2868 – is apparently a compromise that focused only on the plants posing the highest risk. According to the NY Times, it mandates that industry use safer chemicals or processes when DHS and the EPA determine that they are feaisble and cost effective. It does allow for states to pass stricter regulations.

While the House was considering the issue, the Clorox Company announced that it was choosing to convert all of its factories that use chlorine gas to safer chemical processes. The switch should reduce the threat to Americans who live near the rail lines used to transport the chlorine to plants — another point of high vulnerability to terrorist attack or accident.

OMB Watch posted a detailed review of the legislation.

As a result, I’ve been thinking about the scope of attention in global health, and about populations and settings that are, for some reason, out of focus right now; one group in particular came to mind.

Between sessions I wrote a short piece on the topic – It’s up now over at Pulse + Signal.

One of my favorites was a talk by Peter Wittner, of consulting group Interpharm, who gave a very interesting talk on the evolution of the respiratory (inhaled) generic market and the dissolving boundary between the traditional innovators and the generic manufacturers.

A recent article in the Economist – “Generically Challenged,” from the World in 2010 issue – lays out the growing interest of the major innovators in the generics drug companies, prompted in part by the “looming patent cliff.” According to EvaluatePharma, the total sales of prescription drugs at risk from patent expiry is set to more than double from 2010 to 2011. Vijay Vaitheeswaran argues that government attempts to control prices are propelling generics in high income countries, while in low income countries it is the growing middle classes. In fact, emerging economies already make up more than half of total global pharmaceutical sales.

Back in London, Wittner drew attention to the appeal of the branded generics approach. These are products made of off-patent formulations but sold for premium price. By his account, one company (Norton) was able to recognize that a lengthy generic name (sodium cromoglycate, rather than Intal) was hindering physicians from writing a prescription. In response, they adopted a branded generic approach, raised the price of their product, and labeled it Cromolyn. The Economist predicts that the major drugs firms are set to aggressively enter the branded generics market next year. It highlights a number of recent acquisitions and alliances between the big drugs firms and Asian generics firms like Ranbaxy.

Wittner also outlined the barriers facing the generics companies (such as proving bioequivalence) and some of the complicated struggles around patents in the respiratory drug market. There are several examples that illustrate how skilled generics companies have become at attacking weak patents; he discussed the recent European challenges to the Seretide and Symbicort patents in particular.

Finally, Wittner offered great bit on the lateral thinking and agility of generics companies, who are developing and protecting innovative new respiratory delivery devices and active pharmaceutical ingredients (API). He closed with some observations on the uncertainty around the potential competitors set to emerge from the Asian market and outlined some of the competitive advantages that Asian companies have, including a favorable regulatory environment.