Gonzalo G. Alvarez

Overdiagnosis of asthma in obese and nonobese adults

Background: It is unclear whether asthma is overdiagnosed in developed countries, particularly among obese individuals, who may be more likely than nonobese people to experience dyspnea. Methods: We conducted a longitudinal study involving nonobese (body mass index 20–25) and obese (body mass index ≥ 30) individuals with asthma that had been diagnosed by a physician. Participants were recruited from 8 Canadian cities by means of random-digit dialing. A diagnosis of current asthma was excluded in those who did not have evidence of acute worsening of asthma symptoms, reversible airflow obstruction or bronchial hyperresponsiveness, despite being weaned off asthma medications. We stopped asthma medications in those in whom a diagnosis of asthma was excluded and assessed their clinical outcomes over 6 months. Results: Of 540 individuals with physician-diagnosed asthma who participated in the study, 496 (242 obese and 254 nonobese) could be conclusively assessed for a diagnosis of asthma. Asthma was ultimately excluded in 31.8% (95% confidence interval [CI] 26.3%–37.9%) in the obese group and in 28.7% (95% CI 23.5%–34.6%) in the nonobese group. Overdiagnosis of asthma was no more likely to occur among obese individuals than among nonobese individuals (p = 0.46). Of those in whom asthma was excluded, 65.5% did not need to take asthma medication or seek health care services because of asthma symptoms during a 6-month follow-up period. Interpretation: About one-third of obese and nonobese individuals with physician-diagnosed asthma did not have asthma when objectively assessed. This finding suggests that, in developed countries such as Canada, asthma is overdiagnosed.

The Prevalence and Drug Sensitivity of Tuberculosis among Patients Dying in Hospital in KwaZulu-Natal, South Africa: A Postmortem Study

A postmortem study by Ted Cohen and colleagues reveals a huge toll of tuberculosis among patients dying in hospitals in KwaZulu-Natal, South Africa.

Reevaluation of Diagnosis in Adults With Physician-Diagnosed Asthma.

Importance Although asthma is a chronic disease, the expected rate of spontaneous remissions of adult asthma and the stability of diagnosis are unknown. Objective To determine whether a diagnosis of current asthma could be ruled out and asthma medications safely stopped in randomly selected adults with physician-diagnosed asthma. Design, Setting, and Participants A prospective, multicenter cohort study was conducted in 10 Canadian cities from January 2012 to February 2016. Random digit dialing was used to recruit adult participants who reported a history of physician-diagnosed asthma established within the past 5 years. Participants using long-term oral steroids and participants unable to be tested using spirometry were excluded. Information from the diagnosing physician was obtained to determine how the diagnosis of asthma was originally made in the community. Of 1026 potential participants who fulfilled eligibility criteria during telephone screening, 701 (68.3%) agreed to enter into the study. All participants were assessed with home peak flow and symptom monitoring, spirometry, and serial bronchial challenge tests, and those participants using daily asthma medications had their medications gradually tapered off over 4 study visits. Participants in whom a diagnosis of current asthma was ultimately ruled out were followed up clinically with repeated bronchial challenge tests over 1 year. Exposure Physician-diagnosed asthma established within the past 5 years. Main Outcomes and Measures The primary outcome was the proportion of participants in whom a diagnosis of current asthma was ruled out, defined as participants who exhibited no evidence of acute worsening of asthma symptoms, reversible airflow obstruction, or bronchial hyperresponsiveness after having all asthma medications tapered off and after a study pulmonologist established an alternative diagnosis. Secondary outcomes included the proportion with asthma ruled out after 12 months and the proportion who underwent an appropriate initial diagnostic workup for asthma in the community. Results Of 701 participants (mean [SD] age, 51 [16] years; 467 women [67%]), 613 completed the study and could be conclusively evaluated for a diagnosis of current asthma. Current asthma was ruled out in 203 of 613 study participants (33.1%; 95% CI, 29.4%-36.8%). Twelve participants (2.0%) were found to have serious cardiorespiratory conditions that had been previously misdiagnosed as asthma in the community. After an additional 12 months of follow-up, 181 participants (29.5%; 95% CI, 25.9%-33.1%) continued to exhibit no clinical or laboratory evidence of asthma. Participants in whom current asthma was ruled out, compared with those in whom it was confirmed, were less likely to have undergone testing for airflow limitation in the community at the time of initial diagnosis (43.8% vs 55.6%, respectively; absolute difference, 11.8%; 95% CI, 2.1%-21.5%). Conclusions and Relevance Among adults with physician-diagnosed asthma, a current diagnosis of asthma could not be established in 33.1% who were not using daily asthma medications or had medications weaned. In patients such as these, reassessing the asthma diagnosis may be warranted.

A Comparison of Obese and Nonobese People With Asthma Exploring an Asthma-Obesity Interaction

OBJECTIVE The objectives of our study were to compare patient characteristics and severity of disease in obese and normal-weight-confirmed people with asthma and to explore reasons for misdiagnosis of asthma, including potential interactions with obesity. METHODS We randomly selected patients with physician-diagnosed asthma from eight Canadian cities. Asthma diagnosis was confirmed via a sequential lung function testing algorithm. Logistic analysis was conducted to compare obese and normal-weight-confirmed people with asthma and to assess characteristics associated with misdiagnosis of asthma. Interaction with obesity was investigated. RESULTS Complete assessments were obtained on 496 subjects who reported physician-diagnosed asthma (242 obese and 254 normal-weight subjects); 346 had asthma confirmed with sequential lung testing, and in 150 subjects a diagnosis of asthma was ruled out. Obese subjects with asthma were significantly more likely to be men, have a history of hypertension and gastroesophageal reflux disease, and have a lower FEV(1) compared with normal-weight subjects with asthma. Older subjects, men, and subjects with higher FEV(1) were more likely to have received misdiagnoses of asthma. Obesity was not an independent predictor of misdiagnosis, however there was an interaction between obesity and urgent visits for respiratory symptoms. The odds ratio for receiving a misdiagnosis of asthma for obese individuals as compared with normal-weight individuals was 4.08 (95% CI, 1.23-13.5) for those with urgent visits in the past 12 months. CONCLUSIONS Obese people with asthma have lower lung function and more comorbidities compared with normal-weight people with asthma. Obese individuals who make urgent visits for respiratory symptoms are more likely to receive a misdiagnosis of asthma.

A comparative examination of tuberculosis immigration medical screening programs from selected countries with high immigration and low tuberculosis incidence rates

BackgroundTuberculosis (TB) in migrants is an ongoing challenge in several low TB incidence countries since a large proportion of TB in these countries occurs in migrants from high incidence countries. To meet these challenges, several countries utilize TB screening programs. The programs attempt to identify and treat those with active and/or infectious stages of the disease. In addition, screening is used to identify and manage those with latent or inactive disease after arrival. Between nations, considerable variation exists in the methods used in migration-associated TB screening. The present study aimed to compare the TB immigration medical examination requirements in selected countries of high immigration and low TB incidence rates.MethodsDescriptive study of immigration TB screening programsResults16 out of 18 eligible countries responded to the written standardized survey and phone interview. Comparisons in specific areas of TB immigration screening programs included authorities responsible for TB screening, the primary objectives of the TB screening program, the yield of detection of active TB disease, screening details and aspects of follow up for inactive pulmonary TB. No two countries had the same approach to TB screening among migrants. Important differences, common practices, common problems, evidence or lack of evidence for program specifics were noted.ConclusionsIn spite of common goals, there is great diversity in the processes and practices designed to mitigate the impact of migration-associated TB among nations that screen migrants for the disease. The long-term goal in decreasing migration-related introduction of TB from high to low incidence countries remains diminishing the prevalence of the disease in those high incidence locations. In the meantime, existing or planned migration screening programs for TB can be made more efficient and evidenced based. Cooperation among countries doing research in the areas outlined in this study should facilitate the development of improved screening programs.

Ocular tuberculosis: diagnostic and treatment challenges

Ocular tuberculosis (TB) is a challenging clinical entity, pre-senting hurdles in diagnosis and management for bothophthalmologists and infectious disease specialists. Earlydiagnosis and prompt treatment may be sight-saving inpatients with ocular TB. However, diagnostic obstacles pre-sent the greatest limitations in understanding and treatingocular TB in 2008.

Cell salvage does not minimize perioperative allogeneic blood transfusion in abdominal vascular surgery: a systematic review.

PurposeTo determine whether the use of cell salvage reduces the proportion of patients receiving at least one unit of allogeneic packed red blood cells during the perioperative period of an elective vascular surgery.SourceWe identified all relevant articles through the combined use of electronic searches of the MEDLINE and EMBASE databases, the Cochrane library as well as hand searching of all randomized clinical trials and review articles. The electronic search included articles published between 1966 and April 2001. The search included textword searches using “autotransfusion,” “cell salvage,” “device,” or Medical Subject Headings “autologous blood transfusion” or a “randomized controlled trials” filter.Principal findingsFive randomized controlled trials (RCT) were identified involving cell salvage and vascular surgeries. In infra renal abdominal aortic aneurysm surgery the risk ratio (the risk of receiving at least one unit of allogeneic red cells) was 0.37 [95% confidence intervals (CI) of 0.06 to 2.36]. In elective aorto-femoral bypass surgery the risk ratio was 0.97 (95% CI of 0.66 to 1.42). The pooled risk ratio for cell salvage in vascular surgery was 0.67 (95% CI of 0.35 to 1.28).ConclusionCell salvage, a commonly used technique to recover red cells from the operative field, has been the subject of several studies in vascular surgery. There is insufficient evidence to recommend the routine use of cell salvage in elective abdominal aortic aneurysm and aorto-femoral bypass surgeries. A large RCT would elucidate whether cell salvage is effective as a blood conservation technique.RésuméObjectifDéterminer si la récupération de sang réduit le nombre de patients qui recevront au moins une unité de concentré de globules rouges allogènes en période périopératoire d’une intervention chirurgicale vasculaire réglée.SourceLes articles pertinents ont été repérés par des recherches électroniques combinées dans MEDLINE et EMBASE, la bibliothèque Cochrane et une recherche manuelle des essais cliniques randomisés et des exposés de synthèse. La recherche électronique comprend des articles publiés entre 1966 et avril 2001 à partir des termes «autotransfusion», «cell salvage», «device» ou de mots clés du domaine médical comme «autologous blood transfusion» ou d’un filtre sur les «randomized controlled trials».Constatations principalesNous avons trouvé cinq études randomisées et contrôlées (ERC) comportant la récupération de sang et la chirurgie vasculaire. L’opération d’un anévrysme aortique abdominal infrarénal présentait un taux de risque (le risque de recevoir au moins une unité de globules rouges allogènes) de 0,37 [intervalle de confiance (IC) de 95 % de 0,06 à 2,36]. Le risque lié au pontage aortofémoral réglé était de 0,97 (IC de 95 % de 0,66 à 1,42). Le risque commun en chirurgie vasculaire était de 0,67 (IC de 95 % de 0,35 à 1,28).ConclusionLa récupération de sang, couramment utilisé pour conserver les globules rouges provenant du champ opératoire, a fait l’objet de quelques études en chirurgie vasculaire. Il n’y a pas de preuve suffisante pour recommander la récupération régulière de sang lors d’opérations pour anévrysme aortique abdominal et de pontages aorto-fémoraux. Une importante ERC pourrait préciser si la récupération de sang est efficace comme technique de conservation du sang.

TAIMA (Stop) TB: The Impact of a Multifaceted TB Awareness and Door-to-Door Campaign in Residential Areas of High Risk for TB in Iqaluit, Nunavut

Background The incidence rate of active tuberculosis (TB) disease in the Canadian Territory of Nunavut has shown a rising trend over the past 10 years. In 2010 it was 60 times greater than the national incidence rate. The objective of the Taima (translates to “stop” in Inuktitut) TB study was to implement and evaluate a public health campaign to enhance existing TB prevention efforts in Nunavut. Methods A TB awareness campaign followed by a door-to-door screening campaign was carried out in Iqaluit, Nunavut. The aim of the campaign was to raise awareness about TB, and to provide in-home screening and treatment for people living in residential areas at high risk for TB. Screening was based on geographic location rather than on individual risk factors. Results During the general awareness campaign an increase in the number of people who requested TB testing at the local public health clinic was observed. However, this increase was not sustained following cessation of the awareness campaign. Targeted TB screening in high risk residential areas in Iqaluit resulted in 224 individuals having TSTs read, and detection of 42 previously unidentified cases of latent TB, (overall yield of 18.8% or number needed to screen = 5.3). These cases of latent TB infection (LTBI) were extra cases that had not been picked up by traditional screening practices (34% relative increase within the community). This resulted in a 33% relative increase in the completion of LTBI treatment within the community. The program directly and indirectly identified 5/17 new cases of active TB disease in Iqaluit during the study period (29.5% of all incident cases). Conclusions While contact tracing investigations remain a cornerstone of TB prevention, additional awareness, screening, and treatment programs like Taima TB may contribute to the successful control of TB in Aboriginal communities.

The feasibility of the interferon gamma release assay and predictors of discordance with the tuberculin skin test for the diagnosis of latent tuberculosis infection in a remote Aboriginal community.

Background The tuberculin skin test (TST) is the standard test used to screen for latent TB infection (LTBI) in the northern Canadian territory of Nunavut. Interferon gamma release assays (IGRA) are T cell blood-based assays to diagnose LTBI. The Bacillus Calmette-Guerin (BCG) vaccine is part of the routine immunization schedule in Nunavut. The objective of this study was to test the feasibility, and predictors of discordance between the Tuberculin Skin Test (TST) and the IGRA assay in a medically under-serviced remote arctic Aboriginal population. Methods Both the TST and QuantiFERON-TB Gold (Qiagen group) IGRA tests were offered to people in their homes as part of a public health campaign aimed at high TB risk residential areas in Iqaluit, Nunavut, Canada. Feasibility was measured by the capacity of the staff to do the test successfully as measured by the proportion of results obtained. Results In this population of predominantly young Inuit who were mostly BCG vaccinated, the use of IGRA for the diagnosis of LTBI was feasible. IGRA testing resulted in more available test results reaching patients (95.6% vs 90.9% p = 0.02) but took longer (median 8 days (IGRA) vs 2 days (TST), p value <0.0001). 44/256 participants (17.2%) had discordant results. Multivariable regression analysis suggested that discordant results were most likely to have received multiple BCG vaccinations (RR 20.03, 95% CI, 3.94–101.82)), followed by BCG given post infancy (RR 8.13, 95% CI, 2.54–26.03)) and then to a lesser degree when BCG was given in infancy (RR 6.43, 95% CI, 1.72–24.85). Interpretation IGRA is feasible in Iqaluit, Nunavut, a remote Arctic community. IGRA testing results in more test results available to patients compared to TST. This test could result in fewer patients requiring latent TB treatment among those previously vaccinated with BCG in a region with limited public health human resources.

Inaccuracy of death certificate diagnosis of tuberculosis and potential underdiagnosis of TB in a region of high HIV prevalence.

Despite the South African antiretroviral therapy rollout, which should reduce the incidence of HIV-associated tuberculosis (TB), the number of TB-attributable deaths in KwaZuluNatal (KZN) remains high. TB is often diagnosed clinically, without microbiologic confirmation, leading to inaccurate estimates of TB-attributed deaths. This may contribute to avoidable deaths, and impact population-based TB mortality estimates. Objectives. (1) To measure the number of cases with microbiologically confirmed TB in a retrospective cohort of deceased inpatients with TB-attributed hospital deaths. (2) To estimate the rates of multi-drug resistant (MDR) and extensively drug resistant (XDR) TB in this cohort. Results. Of 2752 deaths at EDH between September 2006 and March 2007, 403 (15%) were attributed to TB on the death certificate. 176 of the TB-attributed deaths (44%) had a specimen sent for smear or culture; only 64 (36%) had a TB diagnosis confirmed by either test. Of the 39 culture-confirmed cases, 27/39 (69%) had fully susceptible TB and 27/39 (69%) had smear-negative culture-positive TB (SNTB). Two patients had drug monoresistance, three patients had MDR-TB, and one had XDR-TB. Conclusions. Most TB-attributed deaths in this cohort were not microbiologically confirmed. Of confirmed cases, most were smear-negative, culture positive and were susceptible to all first line drugs.