Finding the vulnerable postoperative population: A two-step cluster analysis of the PAIN-OUT registry

BACKGROUND

Identifying predictors of poor postoperative outcomes is crucial for planning personalized pain treatments. The aim of this study was to examine pain outcomes using cluster analysis in N=2,678 patients from the PAIN-OUT registry at first postoperative day.

METHODS

Indicator variables of the clustering analysis assessed multiple domains, such as clinical and surgical conditions, analgesic-anesthetic variables, desire for more pain treatment and outcome variables of the International Pain Outcome Questionnaire (IPO) summarized as factor scores.

RESULTS

Two-step cluster identified the three-cluster solution as the optimal. Two empirical groups (C1 and C2) included patients with good postoperative outcomes discriminated by peripheral nerve block use, while the other cluster (C3) grouped patients with the worst outcomes, where all patients desired more pain treatment. C3 comprised about 20% of the participants, mostly lower limb, abdominal and spine procedures. The best predictors of belonging to C3 included younger age, being male, preoperative opioid use, bone and fracture reduction procedures, institution, number of comorbidities and morphine equivalents in the recovery room.

CONCLUSIONS

IPO factor scores can be used to select pain outcomes phenotypes in large clinical databases. Most of the predictors were present before the recovery period so perioperative planning should focus in the preoperative and intraoperative periods.

Factors Associated With the Risk of Developing Moderate to Severe Acute Postoperative Pain After Primary Total Knee Arthroplasty: Results From the PAIN OUT Registry

BACKGROUND

Total knee arthroplasty (TKA) is one of the most common procedures in orthopedic surgery and not always matches with patient's expectations of pain relief and function improvement. The aim of this study was to assess risk factors for developing moderate to severe acute postoperative pain (APOP) after TKA using the PAIN OUT questionnaire.

METHODS

Prospective, multicentre, international cohort study within the PAIN OUT project. Patients' outcomes were measured with 11-point numerical rating scales (0 = null, 10 = worst possible). Patient and analgesic/anesthetic treatment were assessed. Odds ratio for moderate-severe pain was calculated for each variable and if they were statistically significant in the univariate logistic model, variables were fitted into a multivariate logistic regression model. The effect size was assessed by Cohen's d coefficient.

RESULTS

In total, 968 patients were evaluated. The multivariate model identified chronic preoperative pain (P < .001), general anesthesia (P = .020), and receiving chronic opioids before (P = .020) or after the surgery (P < .001) as factors associated with moderate-severe APOP. No protective factors were observed.

CONCLUSIONS

Our model identified several risk factors for APOP. From our results, preoperative chronic pain, general anesthesia and the use of opioid analgesics could be predictors for higher APOP. These findings may help establish new strategies for the treatment of pain in TKR. More studies should be carried out to identify acute pain predictors and to develop better strategies of pain management for risk patients.

Non-Pharmacological Methods and Post-Operative Pain Relief: An Observational Study

Background

Non-pharmacological methods (NPMs) like cold packs, acupuncture, meditation or distractions are supposed to ease acute post-surgical pain.

Objectives

This study assessed how frequently these methods are used in clinical routine and if their use is associated with pain relief or with the wish for more pain treatment.

Methods

Data from the world’s largest acute post-operative pain registry, PAIN OUT, was used for this study. In PAIN OUT, patients report their pain levels and side effects related to pain therapy after surgery. Overall, 15 different NPMs were tested for their association with pain relief and the wish for more pain treatment using Mann-Whitney U test, Kruskal-Wallis test, General Linear Model, and Logistic Regression. The researchers adjusted for age and gender, and specifically looked at the three most frequent surgeries: total knee replacement, total hip replacement, and laparoscopic cholecystectomy.

Results

Data of 14 767 patients from 12 European hospitals were analyzed. Overall, 6563 (44.4%) patients used at least one NPM; with distraction and cold packs being the most frequently used. The 8204 (55.6%) patients, who did not use NPMs had little yet significantly more pain relief than patients, who used them (means of 71.2% ± 27.9% versus 68.6% ± 25.7%, P < 0.001). Using NPMs does not affect the wish for more pain treatment. This is true for every single NPM. The only exceptional sub-group included total knee replacement patients, where a positive effect of NPMs was observed.

Conclusions

Some NPMs are widely used while others are rarely applied. Their association with pain relief is doubtful. These findings add to a rather contradictory literature. Advantages and disadvantages of applying NPMs solely for pain relief should thus be considered carefully.

Improving perioperative pain management: a preintervention and postintervention study in 7 developing countries

Supplemental Digital Content is Available in the Text.

Introduction:

The burden of untreated postoperative pain is high.

Objective:

This study assessed feasibility of using quality improvement (QI) tools to improve management of perioperative pain in hospitals in multiple developing countries.

Methods:

The International Pain Registry and Developing Countries working groups, from the International Association for the Study of Pain (IASP), sponsored the project and PAIN OUT, a QI and research network, coordinated it, and provided the research tools. The IASP published a call about the project on its website. Principal investigators (PIs) were responsible for implementing a preintervention and postintervention study in 1 to 2 surgical wards in their hospitals, and they were free to choose the QI intervention. Trained surveyors used standardized and validated web-based tools for collecting findings about perioperative pain management and patient reported outcomes (PROs). Four processes and PROs, independent of surgery type, assessed effectiveness of the interventions.

Results:

Forty-three providers responded to the call; 13 applications were selected; and PIs from 8 hospitals, in 14 wards, in 7 countries, completed the study. Interventions focused on teaching providers about pain management. Processes improved in 35% and PROs in 37.5% of wards.

Conclusions:

The project proved useful on multiple levels. It offered PIs a framework and tools to perform QI work and findings to present to colleagues and administration. Management practices and PROs improved on some wards. Interpretation of change proved complex, site-dependent, and related to multiple factors. PAIN OUT gained experience coordinating a multicentre, international QI project. The IASP promoted research, education, and QI work.

Age and preoperative pain are major confounders for sex differences in postoperative pain outcome: A prospective database analysis

Objectives

Current literature is in disagreement regarding female sex as a risk factor for pain after surgery. We hypothesized, that sex differences exist but that they are influenced by certain factors. Here, we investigated the influence of sex for different clinically relevant postoperative pain (POP) outcome parameters and evaluated the role of assumed confounders for sex differences.

Methods

From 1372 screened patients undergoing orthopedic surgery at the university hospital of Muenster between March 2010 and June 2011, 890 patients were included. The validated International Pain Outcomes questionnaire was used to assess the role of sex for several aspects of POP including pain severity, physical and emotional functional interference as well as the patient’s perceptions of the care they received on the first day after surgery. Assessed confounders were age, preoperative chronic pain, anesthetic technique employed and surgical procedure. All statistical analyses were performed with SPSS Statistics Software 22.

Results

Linear regression analysis demonstrated that sex was a statistically significant risk factor for “worst pain since surgery”. Additionally, significant sex differences in “time spent in severe pain”, “feeling anxious due to pain”, “feeling helpless due to pain” and “opioid consumption since surgery” could be identified. An univariate general linear model showed that “age” and “preoperative pain” were significant confounders for sex differences. Further descriptive subgroup analysis revealed consistent sex differences for several POP outcome variables especially in patients older than 50 years or patients with preoperative chronic pain. However, sex differences disappeared in younger patients and in patients without preoperative pain.

Discussion

Our data confirmed that sex differences exist in pain intensity and frequency, pain interference with feelings and opioid consumption during the first 24 hours postoperatively. However, sex differences were significantly influenced by the factors “age” and “preoperative pain”. These findings may in part explain why clinical studies get different results related to sex differences and renders specific awareness in older women and female patients with preoperative chronic pain.

Open versus Laparoscopic Surgery: Does the Surgical Technique Influence Pain Outcome? Results from an International Registry

Postoperative pain management relevant for specific surgical procedures is debated. The importance of evaluating pain with consideration given to type of surgery and the patient's perspective has been emphasized. In this prospective cohort study, we analysed outcome data from 607 patients in the international PAIN OUT registry for assessment and comparison of postoperative pain outcome within the 24 first hours after laparoscopic and open colonic surgery. Patients from the laparoscopic group scored minimum pain at a higher level than the open group (P = 0.012). Apart from minimum pain, no other significant differences in patient reported outcomes were observed. Maximum pain scores >3 were reported from 77% (laparoscopic) and 68% (open) patients (mean ≥ 5 in both groups). Pain interference with mobilization was reported by 87–93% of patients. Both groups scored high levels of patient satisfaction. In the open group, a higher frequency of patients received a combination of general and regional anaesthesia, which had an impact of the minimum pain score. Our results from registry data indicate that surgical technique does not influence the quality of postoperative pain management during the first postoperative day if adequate analgesia is given.

Present-day challenges and future solutions in postoperative pain management: results from PainForum 2014

This paper is a summary of presentations on postoperative pain control by the authors at the 2014 PainForum meeting in People's Republic of China. Postoperative pain is often untreated or undertreated and may lead to subsequent chronic pain syndromes. As more procedures migrate to the outpatient setting, postoperative pain control will become increasingly more challenging. Evidence-based guidelines for postoperative pain control recommend pain assessment using validated tools on a consistent basis. In this regard, consistency may be more important than the specific tool selected. Many hospitals have introduced a multidisciplinary acute pain service (APS), which has been associated with improved patient satisfaction and fewer adverse events. Patient education is an important component of postoperative pain control, which may be most effective when clinicians chose a multimodal approach, such as paracetamol (acetaminophen) and opioids. Opioids are a mainstay of postoperative pain control but require careful monitoring and management of side effects, such as nausea, vomiting, dizziness, and somnolence. Opioids may be administered using patient-controlled analgesia systems. Protocols for postoperative pain control can be very helpful to establish benchmarks for pain management and assure that clinicians adhere to evidence-based standards. The future of postoperative pain control around the world will likely involve more and better established APSs and greater communication between patients and clinicians about postoperative pain. The changes necessary to implement and move forward with APSs is not a single step but rather one of continuous improvement and ongoing change.

Acute pain medicine in anesthesiology

The American Academy of Pain Medicine and the American Society for Regional Anesthesia have recently focused on the evolving practice of acute pain medicine. There is increasing recognition that the scope and practice of acute pain therapies must extend beyond the subacute pain phase to include pre-pain and pre-intervention risk stratification, resident and fellow education in regional anesthesia and multimodal analgesia, as well as a deeper understanding of the pathophysiologic mechanisms that are integral to the variability observed among individual responses to nociception. Acute pain medicine is also being established as a vital component of successful systems-level acute pain management programs, inpatient cost containment, and patient satisfaction scores. In this review, we discuss the evolution and practice of acute pain medicine and we aim to facilitate further discussion on the evolution and advancement of this field as a subspecialty of anesthesiology.

Patients' perception of postoperative pain management: validation of the International Pain Outcomes (IPO) questionnaire

PAIN OUT is a European Commission-funded project aiming at improving postoperative pain management. It combines a registry that can be useful for quality improvement and research using treatment and patient-reported outcome measures. The core of the project is a patient questionnaire-the International Pain Outcomes questionnaire-that comprises key patient-level outcomes of postoperative pain management, including pain intensity, physical and emotional functional interference, side effects, and perceptions of care. Its psychometric quality after translation and adaptation to European patients is the subject of this validation study. The questionnaire was administered to 9,727 patients in 10 languages in 8 European countries and Israel. Construct validity was assessed using factor analysis. Discriminant validity assessment used Mann-Whitney U tests to detect mean group differences between 2 surgical disciplines. Internal consistency reliability was calculated as Cronbach's alpha. Factor analysis resulted in a 3-factor structure explaining 53.6% of variance. Cronbach's alpha at overall scale level was high (.86), and for the 3 subscales was low, moderate, or high (range, .53-.89). Significant mean group differences between general and orthopedic surgery patients confirmed discriminant validity. The psychometric quality of the International Pain Outcomes questionnaire can be regarded as satisfactory.

PERSPECTIVE

The International Pain Outcomes questionnaire provides an instrument for postoperative pain assessment and improvement of quality of care, which demonstrated good psychometric quality when translated into a variety of languages in a large European and Israeli patient population. This measure provides the basis for the first comprehensive postoperative pain registry in Europe and other countries.

The impact of early postoperative pain on health-related quality of life

OBJECTIVES

To examine how the severity of postoperative pain affects patient's health-related quality of life (HRQoL) at 1 week following surgery and to compare two generic validated HRQoL instruments.

METHODS

Patients undergoing general or orthopaedic surgery at the Royal London Hospital were randomly sampled. The following patient outcome data were collected EQ-5D (EuroQoL) pre-operatively and the Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R) at 24 hours postoperation; and EQ-5D, Short-Form-12 (SF-12) and APS-POQ-R at 7 days postoperation. The degree of association between pain and HRQoL was assessed using Pearson's correlation coefficient and multivariate generalized linear regression models.

RESULTS

Of the 228 patients included, 166 patients provided data at 7 days. Sixteen percent reported severe pain ≥ 50% of the day at 7 days. The severity of pain on both the APS-POQ-R pain severity and interference and affective impairment domains at 7 days was highly correlated with a decrease in HRQoL as assessed by the SF-12 Physical Component Score (PCS), SF-12 Mental Component Score (MCS), and EQ-5D scores (r = -0.34 to -0.61, P < 0.0001). Multivariate regression analyses showed that irrespective of confounding factors (eg, age, gender, and pre-operative HRQoL) patients with severe postoperative pain experience important reductions in both physical and mental well-being domains of their HRQoL.

CONCLUSIONS

A proportion of patients continue to experience severe pain at 7 days postoperatively, even after minor surgery. HRQoL is strongly associated with the level of pain and provides additional data on the impact of postsurgery pain on patient's function and well-being. Additional studies are needed to elucidate the interaction between pain severity and HRQoL during the peri-operative period.