Comparing the DN4 tool with the IASP grading system for chronic neuropathic pain screening after breast tumor resection with and without paravertebral blocks: a prospective 6-month validation study

One year follow-up on a randomized study investigating serratus anterior muscle and pectoral nerves type I block to reduced neuropathic pain descriptors after mastectomy

Breast cancer is the second most common diagnosed type of cancer in women. Chronic neuropathic pain after mastectomy occurs frequently and is a serious health problem. In our previous single-center, prospective, randomized controlled clinical study, we demonstrated that the combination of serratus anterior plane block (SAM) and pectoral nerve block type I (PECS I) with general anesthesia reduced acute postoperative pain. The present report describes a prospective follow-up study of this published study to investigate the development of chronic neuropathic pain 12 months after mastectomy by comparing the use of general anesthesia alone and general anesthesia with SAM + PECS I. Additionally, the use of analgesic medication, quality of life, depressive symptoms, and possible correlations between plasma levels of interleukin (IL)-1 beta, IL-6, and IL-10 collected before and 24 h after surgery as predictors of pain and depression were evaluated. The results showed that the use of SAM + PECS I with general anesthesia reduced numbness, hypoesthesia to touch, the incidence of patients with chronic pain in other body regions and depressive symptoms, however, did not significantly reduce the incidence of chronic neuropathic pain after mastectomy. Additionally, there was no difference in the consumption of analgesic medication and quality of life. Furthermore, no correlation was observed between IL-1 beta, IL-6, and IL-10 levels and pain and depression. The combination of general anesthesia with SAM + PECS I reduced the occurrence of specific neuropathic pain descriptors and depressive symptoms. These results could promote the use of SAM + PECS I blocks for the prevention of specific neuropathic pain symptoms after mastectomy.Registration of clinical trial: The Research Ethics Board of the Hospital Sirio-Libanes/Brazil approved the study (CAAE 48721715.0.0000.5461). This study is registered at Registro Brasileiro de Ensaios Clinicos (ReBEC), and ClinicalTrials.gov, Identifier: NCT02647385.

Use of regional analgesia to prevent the conversion from acute to chronic pain

PURPOSE OF REVIEW

Chronic post-surgical pain (CPSP) prevalence has not changed over the past decades what questions the efficacy of preventive strategies. Regional analgesia is used to control acute pain, but preventive effect on CPSP remains debated. Failures and future application of regional analgesia to prevent transition from acute to chronic pain will be discussed.

RECENT FINDINGS

After thoracotomy, perioperative regional analgesia does not seem to prevent CPSP. After breast cancer surgery, paravertebral block might prevent CPSP intensity and impact on daily life up to 12 months, particularly in high catastrophizing patients. In knee arthroplasty, perioperative regional analgesia or preoperative genicular nerve neuroablation do not prevent CPSP, although current studies present several bias. The protective role of effective regional analgesia and early pain relief in trauma patients deserves further studies.

SUMMARY

Regional analgesia failure to prevent CPSP development should prompt us to reconsider its perioperative utilization. Patients' stratification, for example high-pain responders, might help to target those who will most benefit of regional analgesia. The impact of regional analgesia on secondary pain-related outcomes such as intensity and neuropathic character despite no difference on CPSP incidence requires more studies. Finally, the preventive effect of regional analgesia targeted interventions on CPSP in patients suffering from severe subacute pain deserves to be assessed.

Neuropathic component of postoperative pain for predicting post-caesarean chronic pain at three months. A prospective observational study

BACKGROUND

Recent investigations have showed that caesarean section (CS) might be a cause of chronic pain, with a consequent decrease in quality of life.

METHODS

Prospective observational study in a Spanish tertiary hospital. Main Outcome measure was to assess early neuropathic characteristics of pain (DN2 score ≥ 3) one week after CS as a potential risk factor for post-caesarean section chronic pain (PCSCP) at three months. Secondary outcome was to identify other risk factors. 610 consecutive consenting patients undergoing CS were interviewed preoperatively, at discharge from recovery room and 24h postoperatively. Telephone follow-up interviews were conducted one week, three months and twelve months following surgery.

RESULTS

We analysed 597 consecutive patients. The incidence of PCSCP at three and twelve postoperative months were 6.2% and 1% respectively. Subjects with NRS score superior to five on movement one week after CS presented higher incidence of PCSCP (NRS superior to five: 19 (52,2%); NRS equal or lower to five: 172 (30,9%); p=0,009). On multivariate analysis neuropathic pain one week after CS was associated with a higher risk of PCSCP (AOR: 1.63 (95% CI: 1.26-2.11; p<0.001). Other identified risk factors for PCSCP were: uterine exteriorization during CS (AOR: 3.89 (95% CI 1.25-12.10; p=0.019) and a lower gestational age (AOR: 0.87 (95% CI: 0.78-0.96; p=0.008).

CONCLUSIONS

Incidence of PCSCP at three and twelve postoperative months was low, 6.2% and 1% respectively. Early neuropathic characteristics of pain after one week measured by neuropathic pain questionnaire, consisting of two questions (DN2) ≥ 3/7 could be used to identify patients at risk for chronic post-surgical pain and develop preventive strategies.

Paravertebral block for the prevention of chronic postsurgical pain after breast cancer surgery

Patients frequently report chronic postsurgical pain (CPSP) after breast cancer surgery (BCS). The paravertebral block (PVB) is an effective technique to reduce acute postoperative pain after BCS, but its efficacy in preventing CPSP is unclear. This meta-analysis evaluates the efficacy of PVB in preventing CPSP after BCS. We searched Medline, Embase, CENTRAL, Database of Abstracts of Reviews of Effects, ClinicalTrials.gov, and WHO International Clinical Trials Registry Platform for studies comparing PVB with control for CPSP prevention after BCS, from inception to April 2020. The primary outcome was CPSP at 6 months, and the secondary outcomes were CPSP at 3 and 12 months, chronic postsurgical neuropathic pain (CPSNP) at 6 months, and PVB-related complications. Data were pooled and analyzed with a random-effects model, and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to evaluate the certainty of evidence. A total of 12 studies were included in the study; data for the 6-month time point from 7 studies (2161 patients) were analyzed, and no difference was found between PVB and control in terms of efficacy in preventing CPSP after BCS (risk ratio (RR) 0.82 (95% CI 0.62 to 1.08)), with a moderate quality of evidence according to the GRADE system. Similar results were obtained at 3 and 12 months (RR 0.78 (95% CI 0.57 to 1.06), RR 0.45 (95% CI 0.14 to 1.41), respectively). Data for the 12-month time point from seven studies (2087 patients) were analyzed and showed that PVB protected against CPSNP, with low quality of evidence (RR 0.51 (95% CI 0.31 to 0.85)). In conclusion, CPSP was not found significantly prevented by PVB after BCS despite the limits in the included studies; nevertheless, PVB could prevent CPSNP by impacting the transition from acute to chronic pain.

Adjuvant administration of hypertonic saline in lumbar epidural intervention may be associated with successful response in patients with probable neuropathic radicular pain Screened by Douleur Neuropathique 4

Background: Chronic lumbar radicular pain often accompanies neuropathic pain. The treatment may follow a screening for probable neuropathic pain rather than the definitive diagnosis, which is often difficult in daily practice. However, interventional management may have limited effects on symptoms in patients with neuropathic radicular pain refractory to conservative treatments. The purpose of this study is to evaluate the factors associated with successful responses after lumbar epidural intervention in patients with chronic lumbar neuropathic radicular pain determined by Douleur Neuropathique 4 (DN4). Methods: We retrospectively reviewed 221 chronic lumbar radicular pain patients using a DN4 questionnaire prior to the epidural interventional procedure. The patients were divided into two groups according to the DN4 questionnaire: <4-point DN4 and ≥4 DN4. The numerical rating scale (NRS) for pain intensity, changes in physical functional status, and the use of pain medication were obtained before and 1 month after the procedure. Successful responder was defined based on robust combination of outcome parameters. The factors associated with successful response were analyzed using univariate and multivariate regression. Results: We found 170 (76.9%) patients with DN4 <4 and 51 (23.1%) with a score ≥4. Among the total 221 patients, 129 (58.4%) were successful responders and 92 (41.6%) were non-responders regardless of DN4 score. We observed a significantly lower proportion of successful responders among patients with a DN4 score ≥4 (22, 43.1%) than patients with a score <4 (107, 62.9%) (P=0.012). After adjusting in multivariate regression analysis, the DN4 score was independently associated with response after lumbar epidural intervention (odds ratio [OR]=0.838; 95% confidence interval [CI]=0.718-0.978; P=0.025). In subgroup logistic regression analysis according to the DN4 score, adjuvant administration of hypertonic saline during epidural interventions in patients with a DN4 score ≥4 (OR=3.71; CI=1.142-12.457; P=0.029) was associated with the success of the lumbar epidural procedure at 1 month. Conclusion: The adjuvant use of hypertonic saline in lumbar epidural interventions may be effective at least 1 month after the intervention in patients with probable neuropathic lumbar radicular pain ≥4 using the DN4.

Preventing pain after breast surgery: A systematic review with meta-analyses and trial-sequential analyses

BACKGROUND AND OBJECTIVE

The aim of this systematic review was to indirectly compare the efficacy of any intervention, administered perioperatively, on acute and persistent pain after breast surgery.

DATABASES AND DATA TREATMENT

We searched for randomized trials comparing analgesic interventions with placebo or no treatment in patients undergoing breast surgery under general anaesthesia. Primary outcome was intensity of acute pain (up to 6 hr postoperatively). Secondary outcomes were cumulative 24-hr morphine consumption, incidence of postoperative nausea and vomiting (PONV), and chronic pain. We used an original three-step approach. First, meta-analyses were performed when data from at least three trials could be combined; secondly, trial sequential analyses were used to separate conclusive from unclear evidence. And thirdly, the quality of evidence was rated with GRADE.

RESULTS

Seventy-three trials (5,512 patients) tested loco-regional blocks (paravertebral, pectoralis), local anaesthetic infiltrations, oral gabapentinoids or intravenous administration of glucocorticoids, lidocaine, N-methyl-D-aspartate antagonists or alpha2 agonists. With paravertebral blocks, pectoralis blocks and glucocorticoids, there was conclusive evidence of a clinically relevant reduction in acute pain (visual analogue scale > 1.0 cm). With pectoralis blocks, and gabapentinoids, there was conclusive evidence of a reduction in the cumulative 24-hr morphine consumption (> 30%). With paravertebral blocks and glucocorticoids, there was conclusive evidence of a relative reduction in the incidence of PONV of 70%. For chronic pain, insufficient data were available.

CONCLUSIONS

Mainly with loco-regional blocks, there is conclusive evidence of a reduction in acute pain intensity, morphine consumption and PONV incidence after breast surgery. For rational decision making, data on chronic pain are needed.

SIGNIFICANCE

This quantitative systematic review compares eight interventions, published across 73 trials, to prevent pain after breast surgery, and grades their degree of efficacy. The most efficient interventions are paravertebral blocks, pectoralis blocks and glucocorticoids, with moderate to low evidence for the blocks. Intravenous lidocaine and alpha2 agonists are efficacious to a lesser extent, but with a higher level of evidence. Data for chronic pain are lacking.

Douleur Neuropathique 4 (DN4) stratifies possible and definite neuropathic pain after surgical peripheral nerve lesion

BACKGROUND

Douleur Neuropathique 4 (DN4) is a screening questionnaire to help identify neuropathic pain (NP) in clinical practice and research. We tested the accuracy of the DN4 questionnaire in stratifying possible NP (pNP) and definite NP (dNP) in patients operated for breast cancer.

METHODS

We studied 163 patients from a longitudinal cohort of breast cancer operated patients 4-9 years after surgery. pNP or dNP were classified according to the NP grading system. Surgeon-verified intercostobrachial nerve resection was used as a confirmatory test for dNP. A receiver-operating characteristic (ROC) curve analysis was performed and the area under the curve (AUC) was calculated to test the diagnostic accuracy (sensitivity, specificity, positive and negative predictive values) of the DN4. Additionally, we studied clinical factors that associated with a positive screening outcome in the interview part of the DN4 (DN4i).

RESULTS

DN4i and DN4 showed significant accuracy in stratifying patients with pNP or dNP with cut-off scores 3 and 4 resulting to sensitivity of 66.2% and 79.4% and specificity of 77.8% and 92.6%, respectively. pNP and dNP patients showed differences in sensory descriptors of pain according to DN4i items. Screening positive on DN4i associated with dNP and younger age.

CONCLUSIONS

Full DN4 could stratify pNP and dNP patients in a chronic postsurgical NP patient group operated for breast cancer. Additionally, DN4i showed significant accuracy in stratifying pNP and dNP, but an examination is necessary to obtain proper accuracy. Demographic factors may have an impact on the screening outcome of DN4i.

SIGNIFICANCE

DN4 stratifies possible and definite postsurgical peripheral neuropathic pain. DN4i may also show this, but full DN4 is more accurate. We confirm DN4i as a valid screening tool for NP.

Neuropathic cancer pain: prevalence, pathophysiology, and management

Neuropathic cancer pain (NCP) is caused by nerve damage attributable to the cancer per se, and/or treatments including chemotherapy, radiotherapy, and surgery; the prevalence is reported to be as high as 40%. The etiologies of NCP include direct nerve invasion or nerve compression by the cancer, neural toxicity, chemotherapy, and radiotherapy. NCP is subdivided into plexopathy, radiculopathy, and peripheral neuropathies, among several other categories. The clinical characteristics of NCP differ from those of nociceptive pain in terms of both the hypersensitivity symptoms (burning, tingling, and an electrical sensation) and the hyposensitivity symptoms (numbness and muscle weakness). Recovery requires several months to years, even after recovery from injury. Management is complex; NCP does not usually respond to opioids, although treatments may feature both opioids and adjuvant drugs including antidepressants, anticonvulsants, and anti-arrhythmic agents, all of which improve the quality-of-life. This review addresses the pathophysiology, clinical characteristics and management of NCP, and factors rendering pain control difficult.

Early postoperative neuropathic pain assessed by the DN4 score predicts an increased risk of persistent postsurgical neuropathic pain

BACKGROUND

Acute neuropathic pain can occur in the postoperative period but any link with persistent post-surgical neuropathic pain remains unclear.

OBJECTIVES

The objectives of this study were to prospectively describe the incidence of acute post-surgical neuropathic pain in a large population using the DN4 (clinician administered) questionnaire and to confirm the hypothetical link between acute and persistent neuropathic pain at 2 months after surgery in a large population using the DN2 (self administered) questionnaire.

DESIGN

A multi-centre, prospective and observational trial.

SETTING

Two consecutive days in 27 hospitals in France.

PATIENTS

Six hundred and eight patients undergoing 13 different types of surgery. Fifteen patients were excluded as data were incomplete, and 229 (38.6%) and 260 (43.8%) were not contactable for assessment at 1 and 2 months after surgery, respectively.

MAIN OUTCOME MEASURES

Pain was evaluated at least 2 h postoperatively on the same day (D0),on the second day (D2) and at 1 and 2 months after surgery (M1 and M2). Pain was assessed using a 10-point Numeric Rating Scale. If the Numeric Rating Scale score was greater than 0, neuropathic pain was assessed using a DN4 (clinician administered) questionnaire or using a DN2 (self-administered) questionnaire. Acute and persistent postsurgical neuropathic pain (PPSNP) were defined respectively by a DN4 score at least 4/10 on day 0 and/or day 2 and a DN2 score at least 3/7 at 2 months after surgery.

RESULTS

Of the 593 patients included, 41.2% were in pain before surgery and 8.2% described neuropathic pain. Early after surgery, the majority of the 593 patients (72.2% on the day of surgery and 71.3% on day 2) experienced acute pain. It was neuropathic in nature in 5.6% of patients (95% CI, 3.6 to 8.3) on the day of surgery and 12.9% (95% CI, 9.7 to 16.7) on day 2. Two months after surgery, PPSNP was present in 33.3% of the 333 patients assessed. Multivariate analysis showed that a DN4 score at least 4/10 on the day of surgery or on day 2 was a significant risk factor for PPSNP [odds ratios 4.22 (95% CI, 2.19 to 8.12)].

CONCLUSION

Our results suggest that early acute postsurgical neuropathic pain significantly increases the risk of persistent post-surgical neuropathic pain.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NTC NCT02826317.

Effect of Propofol on breast Cancer cell, the immune system, and patient outcome

Breast cancer is the second leading cause of cancer death in women. Surgery is the first line of treatment for breast cancer. Retrospective clinical studies suggest that the type of anesthesia administered during oncological surgery may influence patient outcome. Propofol, the widely used intravenous anesthetic agent, may lead to better outcomes compared to volatile anesthetics. Here we review the literature on the effect of propofol in breast cancer cells, the immune system, pain management, and patient outcomes. Evidence from the study of breast cancer cell lines suggests that high concentrations of propofol have both anti-tumor and pro-tumor effects. Propofol and volatile anesthetics have different effects on the immune system. Propofol has also been shown to reduce the development and severity of acute and chronic pain following surgery. Although a retrospective study that included many types of cancer indicated that propofol increases the long-term survival of patients following surgery, the evidence for this in breast cancer is weak. It has been shown that Propofol combined with paravertebral block led to change of serum composition that affects the breast cancer cell behaviors and natural killer cell activity. Prospective studies are in progress and will be finished within 5 years. The existing evidence is not sufficient to warrant changes to current anesthetic management. Further research is needed to clarify the mechanisms by which propofol affects cancer cells and the immune system.

The prevalence of neuropathic pain is high after treatment for breast cancer: a systematic review

Pain is common, but often poorly managed after breast cancer treatment. Screening questionnaires and the Neuropathic Pain Special Interest Group (NeuPSIG) criteria are 2 clinical approaches used to determine whether pain has neuropathic components, which may enable better pain management. The aims of this review were (1) to synthesise data from the literature on neuropathic pain prevalence in women after breast cancer treatment; (2) to investigate whether the prevalence of neuropathic pain differed between studies using screening questionnaires and the NeuPSIG criteria. We searched for studies that administered a validated neuropathic pain screening questionnaire and/or the NeuPSIG criteria to women treated for early-stage (I-III) breast cancer. Thirteen studies using screening questionnaires (N = 3792) and 3 studies using components of the NeuPSIG criteria (N = 621) were included. Meta-analyses were conducted for questionnaire data but not for NeuPSIG criteria data because of inadequate homogeneity. Among all participants treated for early-stage breast cancer, pooled prevalence estimates (95% confidence interval) ranged between 14.2% (8.3-21.4) and 27.2% (24.7-88.4) for studies using screening questionnaires; studies using NeuPSIG criteria reported prevalence rates from 24.1% to 31.3%. Among those who reported pain after treatment, the pooled prevalence estimate (95% confidence interval) of neuropathic pain from screening questionnaires ranged from 32.6% (24.2-41.6) to 58.2% (24.7-88.4); studies using NeuPSIG criteria reported prevalence rates from 29.5% to 57.1%. These prevalence estimates are higher than those reported for other types of cancer, and emphasise the need to assess the contribution of neuropathic pain after breast cancer treatment.

TRIAL REGISTRATION

PROSPERO registration CRD42015029987.

Investigating the validity of the DN4 in a consecutive population of patients with chronic pain

Neuropathic pain is clinically described as pain caused by a lesion or disease of the somatosensory nervous system. The aim of this study was to assess the validity of the Dutch version of the DN4, in a cross-sectional multicentre design, as a screening tool for detecting a neuropathic pain component in a large consecutive, not pre-stratified on basis of the target outcome, population of patients with chronic pain. Patients' pain was classified by two independent (pain-)physicians as the gold standard. The analysis was initially performed on the outcomes of those patients (n = 228 out of 291) in whom both physicians agreed in their pain classification. Compared to the gold standard the DN4 had a sensitivity of 75% and specificity of 76%. The DN4-symptoms (seven interview items) solely resulted in a sensitivity of 70% and a specificity of 67%. For the DN4-signs (three examination items) it was respectively 75% and 75%. In conclusion, because it seems that the DN4 helps to identify a neuropathic pain component in a consecutive population of patients with chronic pain in a moderate way, a comprehensive (physical-) examination by the physician is still obligate.

Chronic Postsurgical Pain Outcomes in Breast Reconstruction Patients Receiving Perioperative Transversus Abdominis Plane Catheters at the Donor Site: A Prospective Cohort Follow-up Study

BACKGROUND

Chronic postsurgical pain (CPSP) is a debilitating and costly condition. Risk factors for CPSP after autologous breast reconstruction have not been clearly established. Previously, we demonstrated that transversus abdominis plane (TAP) catheters delivering intermittent local anesthetic reduced postoperative morphine consumption. This prospective follow-up study aimed to (1) compare the incidence of CPSP after autologous breast reconstruction between patients who received postoperative intermittent TAP catheters with bupivacaine or saline boluses and (2) assess the factors that contribute to the development and maintenance of CPSP in this study cohort.

METHODS

Ninety-three patients who underwent deep inferior epigastric artery perforator or muscle-sparing transverse rectus abdominis breast reconstruction were randomized to receive TAP catheters with bupivacaine or saline postoperatively. Subsequently, patients were followed for a year to assess persistent pain, pain severity, quality of life scores, and functional disability at 6 and 12 months after surgery.

RESULTS

Twenty-four percent and 23% of patients reported CPSP at 6 and 12 months, respectively. There were no significant differences between groups (bupivacaine vs. placebo) on pain-related variables, including incidence of CPSP. Patients who reported greater variability in pain scores at rest over the first 48 hours postoperatively were more likely to have CPSP 6 months, but not 12 months, later.

CONCLUSIONS

Acute postoperative pain variability may contribute to the development of CPSP up to 6 months after autologous breast reconstruction surgery. Neither postoperative use of bupivacaine vs. saline in the TAP catheters nor acute pain severity influenced the 6- or 12-month incidence of CPSP.

The clinical characteristics of neuropathic pain in patients with total brachial plexus avulsion: A 30-case study

Neuropathic pain in patients with total brachial plexus avulsion has always been a sophisticated problem in clinical practice.

OBJECTIVES

For further researches on objective diagnosis, alleviation or even cure of neuropathic pain, we need to conclude the basic clinical features including pain intensity, distribution, type and possible risk factors.

METHODS

Thirty cases of patients with total brachial plexus avulsion were included and their baseline information was collected. Pain was evaluated by Present Pain Index using a visual analog scale; Douleur Neuropathique 4 was used for screening neuropathic pain. For more detailed pain description, the Neuropathic Pain Symptoms Inventory questionnaire and a picture showing the exact pain district were both fulfilled by all the eligible participants. The relationship between neuropathic pain and basic information, injury conditions, accompanied conditions and quality of life was tested.

RESULTS

All the participants were male in both groups. The neuropathic pain group contained 22 patients (73.33%) with the mean age of 30.18±9.47; while 29.00±7.95 in the other group. Patients with neuropathic pain presented variously in pain degree, location, type and time phase, according to the results of the Neuropathic Pain Symptoms Inventory questionnaire. Nevertheless, most pain distributed on the region of hand. Among several related factors, alcohol abuse may be possible risk factors of neuropathic pain (p=0.03). Quality of life was significantly affected by pain (p<0.01).

CONCLUSION

Neuropathic pain in patients with total brachial avulsion was characterized with heterogeneity in pain distribution, intensity, type and also time phase. Bad life habits might be risk factors associated with neuropathic pain. Neuropathic pain might affect quality of life of the patients with total brachial plexus avulsion remarkably.

Validity and Reliability of a Novel Ocular Pain Assessment Survey (OPAS) in Quantifying and Monitoring Corneal and Ocular Surface Pain

PURPOSE

To validate the Ocular Pain Assessment Survey (OPAS), specifically designed to measure ocular pain and quality of life for use by eye care practitioners and researchers.

DESIGN

A single-center cohort study was conducted among patients with and without corneal and ocular surface pain at initial and follow-up visits over a 6-month period. The content of the OPAS was guided by literature review, a body of experts, and incorporating conceptual frameworks from existing pain questionnaires. The Wong-Baker FACES Pain Rating Scale served as the gold standard for measuring the intensity of ocular pain.

PARTICIPANTS

A total of 102 patients aged 18 to 80 years completed the OPAS at the initial visit. A total of 21 patients were followed up after treatment.

METHODS

Indices of validity and internal consistency (Spearman's rank-order, rs, or Pearson's correlation coefficients, rp), and coefficient of reliability (Cronbach's α) were determined in addition to equivalence testing, exploratory factor analysis (EFA), and diagnostic analysis.

MAIN OUTCOME MEASURES

Eye pain intensity was the primary outcome measure, and interference with quality of life (QoL), aggravating factors, associated factors, associated non-eye pain intensity, and self-reported symptomatic relief were the secondary outcome measures.

RESULTS

The OPAS had criterion validity at both initial (rs = 0.71; n = 102; P < 0.01) and follow-up visits (rs = 0.97; n = 21; P < 0.01). Equivalence tests yielded OPAS and gold standard equivalence for both the initial and follow-up visits. The EFA supported 6 subscales (eye pain intensity at 24 hours and 2 weeks, non-eye pain intensity, QoL, aggravating factors, and associated factors) confirming multidimensionality. Cronbach's α >0.83 for all subscales established strong internal consistency, which correlated with the gold standard, including 24-hour eye pain intensity and QoL interference scores (rp = 0.81, 0.64, respectively P < 0.001). At follow-up, reduction in pain scores was accompanied by improvement in all dimensions of the OPAS. Percentage change in QoL correlated to percentage change in the gold standard (rp = 0.53; P < 0.05). The OPAS was sensitive (94%), specific (81%), and accurate (91%), with a diagnostic odds ratio >50.

CONCLUSIONS

The OPAS is a valid, reliable, and responsive tool with strong psychometric and diagnostic properties in the multidimensional quantification of corneal and ocular surface pain intensity, and QoL.