BOSTON — The decision to embark on a weight management program that incorporates pharmacotherapy is one that should be shared by patient and clinician, based on reasonable goals, and must take into account the patient's cardiovascular risk factors, according to Dr. David Arterburn.
“Selecting the right drug for the right patient in primary care is a process of shared decision making, which is a nonpaternalistic approach that is particularly useful when there are no clear best options for the patient,” Dr. Arterburn said at the annual meeting of NAASO, the Obesity Society.
“And arguably, in weight management it's safe to say we can't come to the table knowing that there is one clear best option today,” he said.
The role of the caregiver is to provide the patient with the best available information on benefits, risks, and likely outcomes, and to help set an achievable goal, which generally is a 5%–10% weight loss over 6 months. Many patients want to lose more than that, but they are more likely to succeed with a modest initial goal that can later be renegotiated, explained Dr. Arterburn, an internist at the Center for Health Studies, Seattle, Wash.
Also, even a relatively small 5% reduction in body weight is an amount that is associated with significantly reduced long-term health risks, he said.
Two agents, orlistat and sibutramine, have been approved for long-term use in obesity. Orlistat is a lipase inhibitor that blocks the absorption of approximately 30% of ingested fat, while sibutramine is a norepinephrine, serotonin, and dopamine reuptake inhibitor.
A third agent, phentermine, is a sympathomimetic amine similar to the amphetamines and is recommended only for short-term use of 12 weeks or less.
To be eligible for drug treatment, patients generally must have a body mass index of 30 kg/m
Both orlistat and sibutramine have been shown to be more effective than placebo in clinical trials with patients who were also dieting and exercising. Patients receiving orlistat averaged a 2.89-kg greater weight loss than did those receiving placebo, and in one study, patients on this drug plus diet and exercise were 15% more likely to achieve a 5% weight loss than were those on diet and exercise alone (Diabetes Care 2004;27:155–61).
The effect size has been larger in studies of sibutramine, with patients losing an average of 4.5 kg. “Adults taking sibutramine plus diet and exercise for 1 year were 19%–34% more likely to achieve a 5% weight loss than were those taking placebo,” Dr. Arterburn said.
While both drugs do aid in weight loss, they differ in impact on attendant obesity risk factors. Orlistat has an excellent cardiovascular safety profile, typically showing small improvements in blood pressure, lipids, and glycemic control, and therefore would be a suitable first-line therapy for obese patients with hypertension, cardiovascular disease, or dyslipidemia, he said.
Sibutramine is associated with small increases in both systolic and diastolic blood pressure and so would be more appropriate for the otherwise healthy patient without cardiovascular risk factors. Sibutramine also might be preferable for a patient who is unable or unwilling to tolerate the gastrointestinal side effects of orlistat, he said.
Phentermine is limited by a lack of long-term studies and potential for abuse. Nonetheless, it is still the most commonly prescribed weight-loss drug, largely because of its lower cost, said Dr. Arterburn, also of the department of internal medicine, University of Washington, Seattle.
And the cost of treatment can be a barrier for some patients, with a 30-day supply of 120-mg orlistat and 15-mg sibutramine costing $140 and $115, respectively.
An audience member asked how much weight loss would have to be demonstrated before insurers would be more willing to reimburse for treatment. Dr. Arterburn replied that most payers are not so much interested in the amount of weight lost as in a reduction in disease incidence, reduced hospitalizations, and overall lower costs. “Until we can get studies far enough along to demonstrate the harder outcomes that impact patient health care, we're not going to see widespread adoption of these medications by large organizations.”