Centre for Chronic Disease Prevention and Control
Chronic Respiratory Diseases

Terms and definitions

Age-standardized - A technique used to remove as far as possible the effects of differences in age when comparing two or more populations. In this report, the population 5-year age-specific rates for each year were applied to the 1991 Canadian population (the standard population) in 5-year age groups to obtain the overall yearly rate.

Asthma (ICD code 493) - A chronic disorder characterized by symptoms of cough, shortness of breath, chest tightness and wheeze.

Bronchiolitis (ICD code 466.1) - Inflammation of the smaller airways in the lung usually caused by bacterial or viral infection.

Chronic Obstructive Pulmonary Disease (COPD) (ICD code 490-492, 496) - A chronic disease with shortness of breath, cough and sputum production most commonly caused by chronic bronchitis and emphysema.

Current smoker - Individual was smoking at the time of the interview. A current smoker is either a daily smoker or an occasional smoker.

Cystic fibrosis (ICD code 277.0) - A chronic genetic disease that causes individuals to produce abnormal mucous in the lungs that interferes with breathing and affects the ability of the pancreas to produce sufficient enzymes needed for the digestion of food.

Daily smoker - Individual was smoking cigarettes daily at the time of the interview. Environmental tobacco smoke (ETS) - ETS, also known as passive smoking, refers to exposure from smoke produced from cigarettes.

Former smoker - Individual was not smoking at the time of the interview. However, the individual had smoked at least 100 cigarettes during his/her lifetime.

High sampling variability (NPHS) - The National Population Health Survey samples a segment of the population to obtain an estimate of the prevalence of specific variables. Because only a sample is surveyed rather than the whole population, a coefficient of variation is calculated for each variable estimate. This coefficient is dependent in part on the sample size. When it exceeds a certain level, interpretation requires caution because the actual value could vary considerably from the estimate obtained in the survey. In this report the following values were used to define high sampling variability.

Hospital and mortality projections for COPD - Trends in age- and sex- specific mortality and hospitalization rates from 1971 to 1996 were extrapolated to estimate rates in the future. These rates were then applied to population projections from Statistics Canada to estimate the number of hospitalizations and deaths from COPD in the future.

Hospitalization Diagnosis - Each time an individual leaves hospital (discharge, transfer or death) a record is completed listing one or more diagnoses that contributed to the hospital stay. The Main Diagnosis is the most significant condition responsible for the longest stay in hospital. Up to 15 other conditions that were also present may also be listed. This report uses the Main Diagnosis for all analyses except Figures 1-3, 1-4 and 1-5 where the presence of the specific condition in any one of the first five diagnostic fields was included in the analysis.

Incidence (or incidence rate) - The number of new cases that occur in the population at risk during a specific time period (Incidence rate is the number of new cases divided by number of susceptible individuals in the population commonly during a one-year period).

Income adequacy - This variable is derived for four categories based on household income and the size of the household for 1998 (Statistics Canada).

Influenza (ICD code 487) - Infection by the influenza virus that causes mild to severe respiratory symptoms.

Lung cancer (ICD code 162) - Abnormal growth of lung tissue (neoplasia) Occasional smoker - Individual was smoking cigarettes occasionally (not on a daily basis) at the time of the interview.

Pneumonia (ICD code 480-486) - Inflammation of lung usually caused by bacterial or viral infection. Preterm birth rate - The proportion of live births with a gestational age at birth of less than 37 completed weeks (259 days or less) in a specific place and time.

Prevalence (point prevalence) - The proportion of the population who report a behaviour or have a health problem at a certain point in time.

Respiratory Distress Syndrome (RDS) (ICD code 769) - A condition of newborns that results in breathing difficulties due to a deficiency of lung surfactant, which coats the alveoli (airs sacs) to prevent them for collapsing as the baby exhales.

Respiratory Syncytial Virus (RSV) - A virus that causes both upper and lower respiratory symptoms. It is the underlying cause of most cases of bronchiolitis and pneumonia in children under 2 years of age.