GOTHENBURG, Sweden, Nov. 30 (UPI) — Swedish researchers suggest nasal problems lasting longer than 12 weeks increase the risk of severe asthma.

Investigators from the University of Gothenburg in Sweden also say symptoms of chronic rhinosinusitis — having at least two symptoms of nasal blockage such as runny nose, lack of smell and/or sinus pain lasting more than 12 weeks — further increases the risk of severe asthma.

“Our study strongly supports the concept that nasal disease and asthma often are closely related,” lead researcher Jan Lotvall says in a statement. “Doctors should consider whether asthma patients with symptoms from the nose have severe asthma, possibly requiring more intense intervention.”

The study, published in Respiratory Research, indicates asthma with multiple symptoms is more prevalent than previously thought — comprising 20 percent to 25 percent of all asthmatics.

While the prevalence of asthma remained stable over two decades — about 8.5 percent — the prevalence of severe asthma was 2 percent and higher than expected.

“Individuals reporting multiple asthma symptoms are likely to have a more severe form of asthma, which has been shown to increase the risk of asthma attacks, increases health care utilization and negatively influence quality of life,” Lotvall says.

The study was based on a survey of a random sample of 30,000 individuals, which has a response rate of 62 percent.