The lead author, Dr. Michael R. Charlton of the Mayo Clinic, Rochester, Minnesota, and colleagues point out that obesity is considered to be a metabolic condition, not simply a matter of being very overweight.
Obesity in patients with HCV infection is associated inflammation and insulin resistance, a "prediabetic" abnormality of blood sugar. These patients may also have steatosis, "fatty liver disease;" progression of fibrosis, scarring of the liver; and poor response to interferon and ribavirin, the standard treatment for HCV infection.
Patients with hepatitis C and obesity-related fatty liver disease are also at greater risk for more advanced liver disease.
Weight loss to reduce fat tissue is an important first step in improving response to treatment, the investigators advise. Also important is treatment with diabetes drugs, such as metformin and pioglitazone, to improve insulin sensitivity and reduce fat accumulation in the liver. This might reverse disease progression, the researchers note.
Other approaches to enhance patients' response to combination drug therapy may include longer duration of treatment and higher doses to counteract the decreased response to the drugs. Rather than basing doses on weight, they suggest, drug doses could be based on body mass index, a ratio of height to weight.
"Treatment strategies that focus on improving underlying metabolic factors associated with poor response to combination therapy," conclude the researchers, are "more likely to overcome the low sustained viral response rates observed in obese patients infected with HCV."