An analysis released Thursday identified dozens of potentially avoidable hospital complications that are not being tracked by the government even though some occur frequently and are expensive to treat. Premier, Inc., a consulting company that works with hospitals on improving quality, analyzed 5.5 million patient records to identify 86 common complications that occurred in the hospital and were associated with patient deaths, higher costs or longer lengths of stays. The consultants offered estimates for each condition, which include heart attacks in the hospital, sepsis and acute kidney failure.