One in three fatal asthma attacks worldwide involves a child with a mild form of the disease, and nearly half of all parents are unaware of the death risk, according to a new global survey presented Wednesday.

The European Academy of Allergology and Clinical Immunology said the findings exposed a critical information gap between doctors who treat asthma and the parents of youngsters diagnosed with it.

"Many patients with asthma underestimate their disease severity and overestimate their degree of asthma control," the academy warned in the report issued at its annual conference, held this year in Vienna.

Dr. G. Walter Canonica, of the University of Genoa in Italy, said the survey underscored how effective treatment "is a shared responsibility requiring continuous communication among physicians and children with asthma and their parents."

"One place to start is in the area of treatment side effects ... in many cases, parents are not able to identify these side effects," he said.

Experts said that with each decade, the prevalence of asthma increased 50 percent. Worldwide, more than 300 million people are afflicted and more than 180,000 die of the disease each year, the Global Initiative for Asthma says.

Asthma is a chronic lung disease caused by airway inflammation, and certain stimuli cause the windpipe to become obstructed. Symptoms include wheezing, coughing and a tightened airway that causes shortness of breath and can be life-threatening. Allergies are responsible for more than 50 percent of asthma in adults.

Treatment for the condition costs society more than tuberculosis and HIV/AIDS combined, the European Academy said.

Its survey of 5,482 asthma patients, their doctors and the parents of young sufferers focused on cases in Britain, Canada, France, Germany, Italy, Japan, Spain, Switzerland and the United States. The academy called it the first sweeping global study of what parents do and don't know about the hazards of asthma.

Many parents cut back on treatments such as the use of drug inhalers when their children suffer side effects, the study found. Others switch asthma medications or discontinue treatment altogether, it said, cautioning that doing so "can be dangerous and greatly impact health outcomes."

Reducing or stopping treatment usually means a child's condition worsens, the report warned.

"More than three-fourths of children who are not compliant with their asthma treatment all the time experience at least one of the following: increased symptoms (66 percent), limited physical activity (48 percent), nighttime awakenings (46 percent) and more frequent asthma attacks or exacerbations (40 percent)," it said.

Those who don't follow doctors' orders end up with 38 percent more visits to physicians and are 14 percent more likely to wind up in an emergency room or hospitalized, the survey said.

Experts said that although 59 percent of parents say they comply with their doctors' instructions all the time, only 9 percent of physicians believe it because the child's symptoms are not controlled. And parents and doctors both complain that the other side doesn't initiate discussions about treatment and side effects.

"Patients with asthma, parents, and the physicians who treat them should pay close attention to the findings from this survey, which show that the way we currently treat asthma is unsatisfactory," said Dr. Erkka Valovirta, a pediatrics specialist at Finland's Turku Allergy Center.