Gerald T. O'Connor, PhD, ScD

Hanover, NH- Gerald T. O'Connor, PhD, ScD, of Hanover, New Hampshire, passed away on October 22, 2026, surrounded by his loving family. He was 81. A pioneering epidemiologist, beloved teacher and mentor, devoted husband, father, and grandfather, Gerry lived a remarkable life defined by intellectual curiosity, generosity, humor, and an unwavering belief in the potential of others.

Born in Plainfield, New Jersey, to Frank and Margaret O'Connor, Gerry earned degrees from Columbia University, Boston University, and Harvard University, and completed a fellowship in cardiovascular epidemiology at Harvard Medical School.

Gerry devoted his professional life to a simple but powerful idea: that carefully studying variation in the results of medical care could improve it and save lives. In 1987, he founded the Northern New England Cardiovascular Disease Study Group, bringing together surgeons and cardiologists from every hospital performing heart surgery in Maine, New Hampshire, and Vermont. The group's first landmark study, published in JAMA in 1991, showed that death rates after bypass surgery differed substantially across hospitals and surgeons, even after accounting for how sick the patients were. This approach helped the physicians learn from their data and from one another. Five years later, a follow-up study in JAMA reported that deaths after bypass surgery across the region had fallen by 24 percent, demonstrating the extraordinary potential of physicians working together to improve patient care.

After losing his beloved daughter Colleen to complications of cystic fibrosis at age 20, Gerry brought the same approach to CF care. Using the Cystic Fibrosis Foundation's national patient registry, he showed that a patient's life expectancy could differ by nearly seven years depending on which care center treated them, and he went on to help lead the Foundation's national quality improvement effort. Over the following decade, care and life expectancy improved substantially at cystic fibrosis centers across the country. In 2007, the Foundation honored him with its Richard C. Talamo Distinguished Clinical Achievement Award.

Gerry's impact as an educator and mentor may have been even greater. With Dr. Jack Wennberg, he helped found the Center for the Evaluative Clinical Sciences in 1988 (now The Dartmouth Institute for Health Policy and Clinical Practice) and built its graduate degree programs, which he directed for many years. A gifted teacher, he brought insight, generosity, and infectious enthusiasm to mentoring a generation of health care researchers and leaders, whose collective impact on American health care has been significant.

Nowhere was that spirit more evident than in his role as a father. Gerry adored his four daughters and believed wholeheartedly in their potential. He nurtured their curiosity and independence, from Sunday mornings spent reading newspapers and debating current events to enthusiastic college tours along the East Coast. He encouraged them to think critically, work hard, and care deeply about others, and his pride in their accomplishments knew no bounds. His influence is reflected in the careers his daughters pursued in epidemiology and education, and in the values he instilled in all four of them. To each, he was a beloved father, mentor, hero, and lifelong champion.

Gerry shared his love of the outdoors with his family, teaching them to fly fish, cross-country ski and leading hikes through Vermont's Green Mountains and New Hampshire's White Mountains. Ever prepared, he carried extra mittens and peanut butter cups to make challenging outings more manageable. A gifted woodworker, Gerry crafted beautiful Shaker-style furniture that his family treasures.

Those who knew Gerry will remember not only his brilliant mind and extraordinary accomplishments, but also his warmth, quick wit, and unfailing kindness. He was a man who loved deeply, laughed easily, and made the people around him feel valued and capable of great things.

During the last decade of his life, as Gerry lived with Alzheimer's disease, he received extraordinary love and care from the Asis family who embraced Gerry as one of their own, surrounding him with warmth, laughter, and devotion. Gerry's family will be forever grateful for the kindness and love they shared with him.

Gerry is survived by his wife of 47 years, Mary Ann O'Connor; his daughters, Nancy O'Connor Birkmeyer of Lyme, New Hampshire, Bridget Parker of Winchester, Massachusetts, and Kate O'Connor of Washington, DC; his five beloved grandchildren, Maggie, Jack, and Charlie Birkmeyer, and Evelyn and Sam Parker; and his brother, Richard O'Connor of New Jersey. He was predeceased by his daughter, Colleen Margaret O'Connor.

A celebration of Gerry's life will be held on Saturday, December 5, 2026, at 1:00 p.m. at Rollins Chapel in Hanover, New Hampshire, with a reception to follow. In lieu of flowers, the family welcomes donations to the Cystic Fibrosis Foundation.

Knight Funeral Home has been entrusted with arrangements. Condolences may be expressed in an online guestbook found at www.knightfuneralhomes.com