The authors also found that traditional outcomes measured in patients, including liver histology and ALT levels, do not necessarily correspond with HRQOL differences. A panel of experts convened to consider all the data focused on patient-reported vitality as most relevant to HCV-related quality-of-life effects. They established a minimally clinically important HRQOL difference (also called the "MCID") of 4.2 points on the vitality scale.
About 4 million Americans are infected with HCV. While approximately 20 percent of these people eventually develop cirrhosis, the vast majority of people never exhibit clinically significant liver disease. Still evolving data suggests that HCV can diminish quality-of-life even without causing liver disease, perhaps due to HCV symptoms that do not involve the liver, HCV-related cognitive dysfunction, or an association between HCV and comorbid psychosocial disorders.
To better understand how HCV influences health-related quality-of-life, researchers led by Brennan M.R. Spiegel, M.D., M.S.H.S. and Fasiha Kanwal, M.D., M.S.H.S. of the VA Greater Los Angeles Healthcare System and UCLA, performed the first-ever systematic review of relevant literature. They hoped to establish the minimally clinically important health-related quality-of-life difference in HCV patients so researchers and physicians can better monitor patient outcomes, and better inform patients choosing a management strategy.
The authors examined 32 studies published between January 1990 and June 2004. Fifteen compared HRQOL in HCV patients with that of healthy patients. They showed that HCV patients had a diminished HRQOL, most dramatically in social and physical function, general health, and vitality. Nine studies stratified HRQOL by response to treatment measures. They indicated that HRQOL is consistently worse in patients who fail to achieve sustained viral response. Six studies examined HRQOL by neuropsychosocial effects, such as cognitive dysfunction, depression, emotional distress and stigmatization. These studies revealed large HCV-related HRQOL differences. Finally, five studies stratified HRQOL by traditional markers of liver disease. These showed that subtle histological or biochemical changes were not perceived as clinically important by patients, though large differences in HRQOL were found in patients with cirrhosis.
The expert panel concluded that the vitality scale best captured the HRQOL effects relevant to HCV patients. They generated a mean MCID of 4.2 points on the vitality scale. "This value can be used in everyday clinical practice and in clinical trials," the authors suggest. "For example, physicians can measure patient outcomes by administering the 6-item SF vitality scale during office visits. If a patient fails to achieve an increase of 4.2 points over time, then it implies that the ongoing care has failed to perceptively improve the patient's HRQOL. In clinical trials, the MCID can be used as a yardstick to determine whether patients have benefited from the study intervention."
Since the analysis was limited by estimations of MCID based on existing data, the authors suggest that future research directly measure the MCID. Further, they caution, the vitality scale alone may not capture all the key aspects of HRQOL in HCV.
Still, their findings offer a number of important revelations about health-related quality of life in patients with HCV. "In conclusion," the authors report, "chronic HCV diminishes HRQOL across a wide range of clinical anchors. The impact on HRQOL is highly clinically significant and affects physical, social and mental health domains."
Article: "Impact of Hepatitis C on Health Related Quality of Life: A Systematic Review and Quantitative Assessment," Brennan M.R. Spiegel, Zobair M. Younossi, Ron D. Hays, Dennis Revicki, Sean Robbins, and Fasiha Kanwal, Hepatology; April 2005; Volume 41, Issue 4 (Published Online: March 24, 2005).