This study wishes to investigate if pain by peripheral venous cannulation (PVC) preoperatively, will predict pain levels after 24 h postoperatively. Furthermore, to investigate moderate/severe pain at the postoperatively at the post-anaesthesia care unit (PACU) is associated with increased late (24h) pain. Additionally, if the PACU nurse is able to predict if the patient will be a high pain responder, by using a clinical judgement. Finally to evaluate the patient's pain-levels at home after discharge and investigate for associations between postoperative pain and post-discharge pain.

Postoperative pain remains insufficiently treated in clinically relevant proportions of patients across procedures, but with varying incidences. Preoperative identification of patients at risk for increased postoperative pain may result in stratification of perioperative analgesic protocols, aiming at reducing pain in high-risk patients while avoiding over-treatment in those at low-risk.

Several potential patient-related factors have been suggested as associated with an increased risk of higher postoperative pain levels. Studies indicate a positive correlation between postoperative pain levels and e.g. preoperative pain levels, gender, age and socioeconomically and psychological variables. The Pain Catastrophizing Scale (PCS), has been used to look for associations between psychological variables and levels of early and late pain as well. However, no firm data exist for a clinically useful identification of individual high pain responders.

Preoperative sensory testing of patient's nociception has the potential to predict postoperative pain levels. However, a review dealing with the prediction of postoperative pain based on experimental pain studies demonstrated that quantitative sensory testing was only able to predict 4 - 54% of the variance of the postoperative pain of individual patients. Another recent study of clinically applicable tests suggested that relevant sensitivity and specificity can be achieved, but this has not been translated into clinical practice or confirmed. Thus, no preoperative testing method has proven clinically relevant or useful until now.

A newer pragmatic clinical study indicated that the pain intensity associated with peripheral venous cannulation (PVC) could be used as a simple predictor of the magnitude of early pain levels at one hour postoperatively at the post-anaesthesia care unit (PACU). That study, however, did not test the possible association between venepuncture related pain and later pain levels at 24h.

Another simple method for early identification of those with an intensified need of pain treatment after PACU discharge could be to investigate if higher pain levels early postoperatively at the PACU are associated with higher levels of late postoperative pain. Especially, we find it relevant at the individual patient level to investigate if NRS below 3 (moderate/severe pain) in the early postoperative phase at the PACU is associated with NRS levels above 3 late postoperatively.

Also, it could be relevant to investigate if the PACU-nurses, based on their clinical evaluation, are able to predict if the patient would experience an increased risk of moderate/severe pain after PACU discharge. Such a simple clinical tool of staff's judgement of risk of postoperative pain levels has never been tested before.

The hypothesis is that levels of early and late pain are associated and with a simple clinical related tool it could be possible to identify patients with increased pain levels at 24-hours postoperatively.

With updated fast-track perioperative patient causes, patients often are discharged quickly after the surgical procedure. Often there may be a lack of knowledge on how they manage to return to daily living. Pain can be a major problem for the patients, possibly also at home.

Even though one cannot be certain that patients with severe pain, will contact the hospital after discharge. Not only can pain delay rehabilitation it can also be a major factor for developing chronic pain.

Therefore, it is relevant to monitor the patient's pain-levels, quality of sleep, mood, as well as analgesic use and side-effects at home, using a diary from discharge until 5 days postoperatively. Especially, to investigate if patients with higher postoperative pain levels also experience excess pain-related problems after discharge.

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Inclusion Criteria:

• Patients undergoing total hip arthroplasty in spinal anaesthesia
• Patients who understand and speak Danish or English

Exclusion Criteria:

• Patients who cannot cooperate with the study
• Alcohol and drug dependency as judged by the investigator
• Patients in need of urgent surgery
• Patients whom first Peripheral Venous Cannulation attempt was unsuccessful

Patients undergoing total hip arthroplasty (THA) at Zealand University Hospital, Koege meeting the inclusion criteria