WASHINGTON – Irregular heartbeat. Prostate cancer. Back pain. Hearing loss. The government is about to spend millions to try to uncover the best treatments for scores of ailments – and how to handle these four biggies leads a list of top 100 questions that doctors need answered.

One of medicine’s secrets: Doctors often have to guess at which treatment or test is best for a certain patient. There’s very little good scientific evidence comparing them. As part of the economic stimulus package, Congress set aside a down payment of $1.1 billion to start figuring that out, so patients don’t waste time and money on poor choices.

But where to start? Tuesday, the prestigious Institute of Medicine delivered a blueprint – the top 100 priorities to study first.

“This program is a program about improving decisions for patients,” said Dr. Harold Sox of the American College of Physicians, who co-chaired the IOM report.

Some of the questions may surprise patients and families. High on the list:

• Is medication or a surgical fix better for the irregular heartbeat called atrial fibrillation that afflicts 2 million Americans?

• What’s best for early stage prostate cancer – various surgeries, different types of radiation, or so-called watchful waiting?

• What are the pros and cons of new hearing aids, cochlear implants and other devices for age-related hearing loss?

• How effective are numerous treatments for attention deficit hyperactivity disorder – medications, cognitive-behavioral therapy, biofeedback, parent training?

• When should cancer patients have an MRI, a CT scan or PET scan, and when are the scans a waste?

• Which of myriad treatments, from anti-inflammatories to exercises, are best for low back pain?

The advisory group didn’t stop at the doctor’s office but considered ways of preventing health problems, too. So the report also urges comparing how schools can help fight childhood obesity, from meal programs to physical education to restricting vending machines. And since half of all pregnancies are unplanned, the report calls for testing novel strategies like over-the-counter access to birth control pills.

At issue is the “comparative effectiveness” of various treatments and tests for illnesses and ailments. These winners-and-losers questions drive fierce opposition from drug makers and others who have a financial stake in the outcome. That kind of lobbying has left the nation with a scattershot method for determining best medical practices.

The IOM panel was clear: The new program is not about rationing care – it doesn’t call for insurers to use the results for coverage decisions – but about finding unbiased information to make the best choices for a given patient. To do that, the research must include typical patients – usually sicker ones than drug companies enroll in the studies required for sales approval – the report stressed.