Selected underlying medical conditions in patients hospitalized with laboratory-confirmed influenza (Influenza Hospitalization Surveillance Network 2017–2018). Selected underlying medical conditions in patients hospitalized with laboratory-confirmed influenza (Influenza Hospitalization Surveillance Network 2017–2018). Asthma includes a medical diagnosis of asthma or a reactive airway disease. Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, pulmonary hypertension, and aortic stenosis; hypertension disease alone is not included. Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease. Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV and/or AIDS, and individuals taking immunosuppressive medications. Metabolic disorders include conditions such as diabetes mellitus, thyroid dysfunction, adrenal insufficiency, and liver disease. Neurologic disorders include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction. Neuromuscular disorders include conditions such as multiple sclerosis and muscular dystrophy. Obesity was assigned if indicated in a patient's medical chart of if BMI was >30. Pregnancy percentage was calculated by using the number of female case patients between 15 and 44 years of age as the denominator. Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance. No known condition indicates that the case patient did not have any known underlying medical condition indicated in the medical chart at the time of hospitalization. (Reprinted from Centers for Disease Control and Prevention. FluView 2017–2018 preliminary data as of August 18, 2018. Available at: gis.cdc.gov/grasp/fluview/FluHospChars.html.)‏ COMMITTEE ON INFECTIOUS DISEASES Pediatrics 2018;142:e20182367 ©2018 by American Academy of Pediatrics