How to load distinct items into llblgen pro collection

Question

I have a collection like the code below. I load all items from table. How to load just distinct items on specific field?

 var objlogcollection = new ClsfIcdNineToClsfIcdTenDiagnosisCollection();

 IPredicateExpression filter = new PredicateExpression();
 filter.Add(new FieldCompareValuePredicate(ClsfIcdNineToClsfIcdTenDiagnosisFields.ClsfIcdNineCodeFormatted, ComparisonOperator.NotEqual, ClsfIcdNineToClsfIcdTenDiagnosisFields.ClsfIcdNineCodeFormatted));
 objlogcollection.GetMulti(null);