Ailing US former First Lady Barbara Bush, who is in "failing health", has declined further medical treatment and will spend her time in "comfort care", a family spokesman has said. Bush, 92, is being cared for at her home in Houston and has decided she does not want to go back into the hospital. She has been on oxygen for some time, spokesman Jim McGrath said. The statement did not indicate the nature of Bush's illness but said that she had had a series of recent hospitalisations. "Following a recent series of hospitalisations, and after consulting her family and doctors, Mrs Bush has decided not to seek additional medical treatment and will instead focus on comfort care," McGrath said in a statement. Her husband, former President George H W Bush is with her, as are a daughter Doro and sons Marvin and Neil. Her other sons, former President George W Bush and former Governor Jeb Bush, have been in and out visiting her the past week. McGrath said she has been treated for decades for Graves' disease, which is a thyroid condition. She also had a heart surgery in 2009 for a severe narrowing of her main heart valve and was hospitalised a year before that for surgery on a perforated ulcer. "It will not surprise those who know her that Barbara Bush has been a rock in the face of her failing health, worrying not for herself \u2014 thanks to her abiding faith \u2014 but for others," McGrath said. "She is surrounded by a family she adores, and appreciates the many kind messages and especially the prayers she is receiving," he added. Her husband, at 93, is the longest-lived US president. George H W Bush, the nation's 41st president, has also suffered health issues, and spent a period in intensive care for pneumonia last year. He suffers from a form of Parkinson's disease and uses a wheelchair. The couple have been married for 73 years. Their son, George W Bush, was elected president in 2000 and served two terms as the nation's 43rd president. Barbara Bush is the only woman to have seen both her husband and son sworn in as US president.