Hansen TE, et al. – Researchers conducted this case-control study to identify possible risk factors for current asthma revealed by two studies in Northern Norway in 1985 and 2008, and assessed these factors’ contribution to the increased prevalence of asthma over 23-year period. They found that, in both studies, lower respiratory tract infection (LRTI) was the most important risk factor for current asthma; however, they were unable to determine whether LRTIs have contributed to the increased prevalence of asthma in this population over the specified time period.