Higher doses of intraoperative analgesia are associated with lower levels of persistent pain and less analgesic consumption six months after total hip arthroplasty.

BACKGROUND: Persistent postoperative pain is a major health problem affecting nearly 30% of all patients undergoing total hip arthroplasty. Previous studies have demonstrated an association between the intensity of acute postoperative pain and persistent pain, but this association might be an epiphenomenon of insufficient intraoperative analgesia. In this study, we investigated the association between the intraoperative level of analgesia and the persistent postoperative pain 6 months after surgery. METHODS: We investigated 110 patients undergoing primary total hip arthroplasty under total intravenous general anaesthesia in a prospective cohort study. A highly standardized surgical and a standardized anaesthetic procedure were performed to reduce variability and psychosocial influences were investigated to adjust for confounders. Acute postoperative pain was controlled using patient-controlled analgesia pumps. Postoperative pain intensities and analgesic requirements were monitored for 6 months following surgery. RESULTS: Of 105 patients included in the analysis, 32% continued using daily pain medication 6 months after surgery and reported a median pain level of 4/10. Multivariate analyses confirmed that the amount of intraoperative analgesia is a significant predictor of regular analgesic use and pain intensity 6 months after surgery. CONCLUSIONS: Higher levels of intraoperative analgesia are associated with lower levels of persistent pain and less analgesic consumption 6 months after total hip arthroplasty. Persistent pain may be attributable to intraoperative nociception, which is likely not adequately assessed and suppressed using current clinical measures. SIGNIFICANCE: Our study suggests that lower doses of intraoperative analgesia are associated with higher levels of persistent postoperative pain. Persistent pain may be caused by intraoperative nociception, which is likely not adequately suppressed using current clinical standard analgesic measures.

A multistate, foodborne outbreak of hepatitis A. National Hepatitis A Investigation Team.

BACKGROUND: We investigated a large, foodborne outbreak of hepatitis A that occurred in February and March 1997 in Michigan and then extended the investigation to determine whether it was related to sporadic cases reported in other states among persons who had consumed frozen strawberries, the food suspected of causing the outbreak. METHODS: The cases of hepatitis A were serologically confirmed. Epidemiologic studies were conducted in the two states with sufficient numbers of cases, Michigan and Maine. Hepatitis A virus RNA detected in clinical specimens was sequenced to determine the relatedness of the virus from outbreak-related cases and other cases. RESULTS: A total of 213 cases of hepatitis A were reported from 23 schools in Michigan and 29 cases from 13 schools in Maine, with the median rate of attack ranging from 0.2 to 14 percent. Hepatitis A was associated with the consumption of frozen strawberries in a case-control study (odds ratio for the disease, 8.3; 95 percent confidence interval, 2.1 to 33) and a cohort study (relative risk of infection, 7.5; 95 percent confidence interval, 1.1 to 53) in Michigan and in a case-control study in Maine (odds ratio for infection, 3.4; 95 percent confidence interval, 1.0 to 14). The genetic sequences of viruses from 126 patients in Michigan and Maine were identical to one another and to those from 5 patients in Wisconsin and 7 patients in Arizona, all of whom attended schools where frozen strawberries from the same processor had been served, and to those in 2 patients from Louisiana, both of whom had consumed commercially prepared products containing frozen strawberries from the same processor. CONCLUSIONS: We describe a large outbreak of hepatitis A in Michigan that was associated with the consumption of frozen strawberries. We found apparently sporadic cases in other states that could be linked to the same source by viral genetic analysis.