[Long-term efficacy of lactulose in patients with subclinical hepatic encephalopathy]

To observe the long-term clinical efficacy of lactulose in patients with subclinical hepatic encephalopathy (SHE) and the natural history of this disease.

Patients with SHE diagnosed with psychometric tests (number connection test and digit symbol test) were randomly allocated to control group (Cg), short-term (Stg) and long-term treatment group (Ltg), respectively. Lactulose (15 - 90 ml/day) was orally given to 21 patients in Stg for 8 weeks, and 22 in Ltg for 24 weeks.The drug was not given to 21 patients in Cg. Psychometric test, somatosensory evoked potentials (SEP) and venous blood ammonia concentration (BA) were investigated before and after treatment at 8 week intervals for 6 months of follow-up.

In Ltg, psychometric tests were significantly improved, BA was lowered and N(50) peak latency in SEP was not prolonged as compared with those in Cg, in which psychometric tests and N(50) peak latency gradually worsened during the follow-up. After 8 weeks of treatment, psychometric tests, BA and N(50) peak latency were significantly improved in Stg, but at week 24 they were deteriorated after cessation of treatment. The development of clinical hepatic encephalopathy was more frequent in Cg (40%) and Stg (30%) than in Ltg (5%). One patient each was not followed up after week 24 in Cg and Stg, respectively and 2 patients in Ltg stopped lactulose because of severe diarrhea.

In patients with SHE, long-term treatment with lactulose could lower BA, improve psychometric tests, prevent SEP from getting worse, and eventually cut down the occurrence rate of clinical hepatic encephalopathy.