Comparison of logistic regression versus propensity score when the number of events is low and there are multiple confounders

The aim of this study was to use Monte Carlo simulations to compare logistic regression with propensity scores in terms of bias, precision, empirical coverage probability, empirical power, and robustness when the number of events is low relative to the number of confounders. The authors simulated a cohort study and performed 252,480 trials. In the logistic regression, the bias decreased as the number of events per confounder increased. In the propensity score, the bias decreased as the strength of the association of the exposure with the outcome increased. Propensity scores produced estimates that were less biased, more robust, and more precise than the logistic regression estimates when there were seven or fewer events per confounder. The logistic regression empirical coverage probability increased as the number of events per confounder increased. The propensity score empirical coverage probability decreased after eight or more events per confounder. Overall, the propensity score exhibited more empirical power than logistic regression. Propensity scores are a good alternative to control for imbalances when there are seven or fewer events per confounder; however, empirical power could range from 35% to 60%. Logistic regression is the technique of choice when there are at least eight events per confounder.

What decline in pain intensity is meaningful to patients with acute pain?

Despite widespread use of the 0-10 numeric rating scale (NRS) of pain intensity, relatively little is known about the meaning of decreases in pain intensity assessed by means of this scale to patients. We aimed to establish the meaning to patients of declines in pain intensity and percent pain reduction. Upon arrival to the postanesthesia care unit, postsurgical patients rated their baseline pain intensity on both a 0-10 NRS and on a 4-point verbal scale. Patients whose NRS was higher than 4/10 received intravenous opioids until their pain intensity declined to 4/10 or lower. During opioid titration, patients were asked every 10 min to rate pain intensity on a NRS and to indicate the degree of pain improvement on a 5-point Likert scale from 'no improvement' to 'complete pain relief'. Seven hundred adult patients were enrolled. For patients with moderate pain, a decrease of 1.3 units (20% reduction) corresponded to 'minimal' improvement, a decrease of 2.4 (35% reduction) to 'much' improvement, a decrease of 3.5 units (45% reduction) corresponded to 'very much' improvement. For patients with severe pain, the decrease in NRS pain score and the percentage of pain relief had to be larger to obtain similar degrees of pain relief. The change in pain intensity that is meaningful to patients increases as the severity of their baseline pain increases. The present findings are applicable in the clinical setting and research arena to assess treatment efficacy.

Women experience more pain and require more morphine than men to achieve a similar degree of analgesia

Sex differences in pain perception and in response to opioids have been described, but the findings are inconsistent. We sought to determine the effect of sex on pain perception, morphine consumption, and morphine analgesia after surgery. We designed a prospective cohort study and included 423 women and 277 men who emerged from general anesthesia after surgical procedures and who reported pain intensity of >or=5 on the 0-10 numeric rating scale (NRS). We administered 2.5 mg of morphine IV every 10 min until the pain intensity was <or=4 of 10. Every 10 min, patients rated their pain on the NRS and indicated the degree of pain relief on a 5-point Likert scale. After adjustment for type of operation and age, we found that women had more intense pain and had larger morphine consumption than men. The difference in NRS pain intensity was 0.4 U (95% confidence interval, 0.1-0.6 U). Women required 0.03 mg/kg more morphine than men (95% confidence interval, 0.02-0.04 mg/kg). We conclude that women have more intense pain and require 30% more morphine to achieve a similar degree of analgesia compared with men. Clinicians should anticipate the differences in opioid requirement to avoid undertreatment of pain in women.

IMPLICATIONS

The effect of sex on opioid response is not clear. To determine the effect of sex on morphine consumption and morphine analgesia, we designed a cohort study. We found that women had more intense pain and required 30% more morphine to achieve a similar degree of analgesia compared with men.

Side effects of opioids during short-term administration: effect of age, gender, and race

OBJECTIVE

Little is known about risk factors that increase the risk of development of opioid side effects. Our objective was to evaluate the effect of the type of opioid, age, gender, and race on the incidence of side effects from short-term opioid use.

METHODS

A secondary analysis of a retrospective cohort study in 35 community-based and tertiary hospitals was done. There were 8855 black or white subjects aged 16 years and older. Patients received meperidine (INN, pethidine), morphine, or fentanyl as part of their treatment. Measurements were made to assess the presence of nausea and vomiting and respiratory depression.

RESULTS

Of the patients, 26% had nausea and vomiting and 1.5% had respiratory depression after opioid administration. After adjustment for opioid dose, route of administration, age, gender, and race, meperidine produced less nausea and vomiting (odds ratio [OR] = 0.7; 95% confidence interval [CI], 0.5-0.8) and less respiratory depression (OR = 0.6; 95% CI, 0.2-0.9) than morphine. The risk of respiratory depression increased with age. Compared with patients aged between 16 and 45 years, those aged between 61 and 70 years had 2.8 times the risk of development of respiratory depression (95% CI, 1.2-6.6); those aged between 71 and 80 years had 5.4 times the risk (95% CI, 2.4-11.8); and those aged older than 80 years had 8.7 times the risk (95% CI, 3.8-20.0). Men had less nausea and vomiting than women (OR = 0.5; 95% CI, 0.4-0.6). White subjects had more nausea and vomiting than black subjects (OR = 1.4; 95% CI, 1.1-1.7).

CONCLUSIONS

Meperidine produced fewer side effects than morphine during short-term use. The risk of respiratory depression increases substantially after 60 years of age. Women have nausea and vomiting more often than men. The effect of race deserves further investigation.

Music for pain relief

BACKGROUND

The efficacy of music for the treatment of pain has not been established.

OBJECTIVES

To evaluate the effect of music on acute, chronic or cancer pain intensity, pain relief, and analgesic requirements.

SEARCH STRATEGY

We searched The Cochrane Library, MEDLINE, EMBASE, PsycINFO, LILACS and the references in retrieved manuscripts. There was no language restriction.

SELECTION CRITERIA

We included randomized controlled trials that evaluated the effect of music on any type of pain in children or adults. We excluded trials that reported results of concurrent non-pharmacological therapies.

DATA COLLECTION AND ANALYSIS

Data was extracted by two independent review authors. We calculated the mean difference in pain intensity levels, percentage of patients with at least 50% pain relief, and opioid requirements. We converted opioid consumption to morphine equivalents. To explore heterogeneity, studies that evaluated adults, children, acute, chronic, malignant, labor, procedural, or experimental pain were evaluated separately, as well as those studies in which patients chose the type of music.

MAIN RESULTS

Fifty-one studies involving 1867 subjects exposed to music and 1796 controls met inclusion criteria. In the 31 studies evaluating mean pain intensity there was a considerable variation in the effect of music, indicating statistical heterogeneity ( I(2) = 85.3%). After grouping the studies according to the pain model, this heterogeneity remained, with the exception of the studies that evaluated acute postoperative pain. In this last group, patients exposed to music had pain intensity that was 0.5 units lower on a zero to ten scale than unexposed subjects (95% CI: -0.9 to -0.2). Studies that permitted patients to select the music did not reveal a benefit from music; the decline in pain intensity was 0.2 units, 95% CI (-0.7 to 0.2). Four studies reported the proportion of subjects with at least 50% pain relief; subjects exposed to music had a 70% higher likelihood of having pain relief than unexposed subjects (95% CI: 1.21 to 2.37). NNT = 5 (95% CI: 4 to 13). Three studies evaluated opioid requirements two hours after surgery: subjects exposed to music required 1.0 mg (18.4%) less morphine (95% CI: -2.0 to -0.2) than unexposed subjects. Five studies assessed requirements 24 hours after surgery: the music group required 5.7 mg (15.4%) less morphine than the unexposed group (95% CI: -8.8 to -2.6). Five studies evaluated requirements during painful procedures: the difference in requirements showed a trend towards favoring the music group (-0.7 mg, 95% CI: -1.8 to 0.4).

AUTHORS' CONCLUSIONS

Listening to music reduces pain intensity levels and opioid requirements, but the magnitude of these benefits is small and, therefore, its clinical importance unclear.

Single-dose intravenous paracetamol or propacetamol for prevention or treatment of postoperative pain: a systematic review and meta-analysis

Paracetamol is the most commonly prescribed analgesic for the treatment of acute pain. The efficacy and safety of i.v. formulations of paracetamol is unclear. We performed a systematic search (multiple databases, bibliographies, any language, to May 2010) for single-dose, randomized, controlled clinical trials of propacetamol or i.v. paracetamol for acute postoperative pain in adults or children. Thirty-six studies involving 3896 patients were included. For the primary outcome, 37% of patients (240/367) receiving propacetamol or i.v. paracetamol experienced at least 50% pain relief over 4 h compared with 16% (68/527) receiving placebo (number needed to treat=4.0; 95% confidence interval, 3.5-4.8). The proportion of patients in propacetamol or i.v. paracetamol groups experiencing at least 50% pain relief diminished over 6 h. Patients receiving propacetamol or paracetamol required 30% less opioid over 4 h and 16% less opioid over 6 h than those receiving placebo. However, this did not translate to a reduction in opioid-induced adverse events (AEs). Similar comparisons between propacetamol or i.v. paracetamol and active comparators were either not statistically significant, not clinically significant, or both. AEs occurred at similar rates with propacetamol or i.v. paracetamol and placebo. However, pain on infusion occurred more frequently in those receiving propacetamol compared with placebo (23% vs 1%). A single dose of either propacetamol or i.v. paracetamol provides around 4 h of effective analgesia for about 37% of patients with acute postoperative pain. Both formulations are associated with few AEs, although patients receiving propacetamol have a higher incidence of pain on infusion.

Addition of ultralow dose naloxone to postoperative morphine PCA: unchanged analgesia and opioid requirement but decreased incidence of opioid side effects

Ultralow doses of naloxone (0.001-0.1 microg/kg) produce analgesia in animal models. However, no clinical study has evaluated the combination of ultralow dose naloxone and morphine using patient-controlled analgesia (PCA). This randomized, double blind controlled study sought to determine if the combination of ultralow dose naloxone and morphine in PCA solutions affects opioid requirements, analgesia, and side effects. Two-hundred and sixty-five patients (18-65 years old) undergoing operations were randomized to receive PCA morphine 1 mg/ml (n=129) or PCA morphine 1 mg/ml plus naloxone 0.6 microg/ml (n=136). We evaluated the numbers of supplemental rescue doses, the cumulative dose of each PCA solution, pain intensity, pain relief, and opioid side effects during the first 24 h after surgery. We found that opioid requirements did not differ significantly between groups. The morphine+naloxone group on average required 0.07 mg more morphine (95% CI -1.1 to 1.3) during the 24 h than the morphine group. Pain intensity levels were also similar in both groups. The morphine+naloxone group had 0.06 units lower (95% CI -0.5 to 0.4) pain intensity levels than the morphine group. The morphine+naloxone group had a lower incidence of nausea and pruritus than the morphine group (P=0.01 for both symptoms). However, the incidence of vomiting, time to tolerate fluids, sedation, and urinary retention were similar between groups (all P values >0.1). The combination of ultralow dose naloxone and morphine in PCA does not affect analgesia or opioid requirements, but it decreases the incidence of nausea and pruritus.

Defining the therapeutic role of local anesthetic sympathetic blockade in complex regional pain syndrome: a narrative and systematic review

OBJECTIVE

There is growing controversy on the value of blocking the sympathetic nervous system for the treatment of complex regional pain syndromes (CRPS). The authors sought to evaluate the efficacy of sympathetic blockade with local anesthetic in these syndromes. In addition, they performed a comprehensive review of the pathophysiology and other treatments for CRPS.

DESIGN

Systematic review of the literature was performed. MEDLINE was searched from 1966 through 1999. The authors identified only three randomized controlled trials (RCTs) that evaluated sympathetic blockade with local anesthetic, but because of differences in study design they were unable to pool the study data. The authors therefore included nonrandomized studies and case series.

INTERVENTIONS

Studies were included if local anesthetic sympathetic blockade was used in at least 10 patients. Studies were excluded if continuous infusion techniques, somatic nerve blocks, or combined sympatholytic therapies were evaluated.

OUTCOME MEASURES

Pain relief was classified as full, partial, or absent. The lack of a comparison group in the studies allowed only the calculation of distribution of the response categories, and the sum of the pooled rates does not equal 100%.

RESULTS

Twenty-nine studies were included that evaluated 1,144 patients. Nineteen studies were retrospective, 5 prospective case series, 3 RCTs, and 2 nonrandomized controlled studies. The quality of the publications was generally poor. Twenty-nine percent of patients had full response, 41% had partial response, and 32% had absent response. It was not possible to estimate the duration of pain relief.

CONCLUSIONS

This review raises questions as to the efficacy of local anesthetic sympathetic blockade as treatment of CRPS. Its efficacy is based mainly on case series. Less than one third of patients obtained full pain relief. The absence of control groups in case series leads to an overestimation of the treatment response that can explain the findings.

The combination of low dose of naloxone and morphine in PCA does not decrease opioid requirements in the postoperative period

The continuous infusion of low doses of naloxone has been reported to decrease postoperative opioid requirements and opioid side effects. However, there is no study that evaluates the effectiveness of the combination of a low dose of naloxone and morphine using patient-controlled analgesia (PCA). This prospective, randomized double-blind controlled study sought to determine if the combination of a low dose of naloxone and morphine in a PCA solution decreases postoperative opioid requirements and pain intensity. One hundred sixty-six patients (18-65 years old) undergoing operations of less than 3 h duration with an American Society of Anesthesiologist physical status I or II were randomized to receive PCA morphine 1 mg/cc plus normal saline or PCA morphine 1 mg/cc plus naloxone 6 microg/cc. Initial PCA settings were 0.5 cc per demand with a lockout time of 10 min. The numbers of 2.5 cc supplemental rescue doses and the cumulative dose of each solution were recorded in the first 24 h after the surgical procedure. Pain intensity and opioid side effects were evaluated every 10 min in the post-anesthesia care unit and every 4 h afterwards. Patient satisfaction was assessed at the end of the 24 h of observation. The morphine+naloxone group had more treatment failures (P=0.0001), higher opioid requirements (P=0.0097), greater pain intensity (P=0.04), less pain relief (P=0.004), and less satisfaction (P=0.01) than the morphine group. The incidence of side effects was similar in both groups (P=0.3). Contrary to previous reports, adding low doses of naloxone to a morphine PCA solution increases opioid requirements and pain.

Tramadol for osteoarthritis

BACKGROUND

Tramadol is increasingly used for the treatment of osteoarthritis because, in contrast to nonsteroidal anti-inflammatory drugs (NSAIDs), tramadol does not produce gastrointestinal bleeding or renal problems, and does not affect articular cartilage.

OBJECTIVES

We sought to determine the analgesic effectiveness, the effect on physical function, the duration of benefit and the safety of oral tramadol in people with osteoarthritis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and LILACS databases up to August 2005.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that evaluated the effect of tramadol or tramadol plus paracetamol on pain levels and/or physical function in people with osteoarthritis. No language restriction was applied.

DATA COLLECTION AND ANALYSIS

We analyzed separately placebo-controlled and active-controlled studies. We used fixed-effect models for the meta-analyses as the results across studies were similar.

MAIN RESULTS

We included eleven RCTs with a total of 1019 participants who received tramadol or tramadol/paracetamol and 920 participants who received placebo or active-control. The placebo-controlled studies indicated that participants who received tramadol had less pain (-8.5 units on a 0 to 100 scale; 95% confidence interval (CI) -12.0 to -5.0) than patients who received placebo. This represents a 12% relative decrease in pain intensity from baseline. Participants who received tramadol had a 37% increase (95% CI 1.2 to 1.5) in the likelihood of reporting moderate improvement (number needed to treat to benefit = 6; 95% CI 4 to 9). Participants who received tramadol had 2.27 times the risk of developing minor adverse events and 2.6 times the risk of developing major adverse events, compared to participants who received placebo. Of every eight people who receive tramadol or tramadol/paracetamol, one will stop taking the medication because of adverse events, number needed to treat to harm (NNTH)= 8 (95% CI 7 to 12) for major adverse events. No conclusion could be drawn on how tramadol or tramadol/paracetamol compared with available pharmacological treatments because of the limited number of studies that evaluated such therapies.

AUTHORS' CONCLUSIONS

Tramadol or tramadol/paracetamol decreases pain intensity, produces symptom relief and improves function, but these benefits are small. Adverse events, although reversible and not life threatening, often cause participants to stop taking the medication and could limit tramadol or tramadol plus paracetamol usefulness.

Emotional disclosure through patient narrative may improve pain and well-being: results of a randomized controlled trial in patients with cancer pain

Narrative medicine is based upon physicians' awareness of patients' narration of their suffering, their hopes, and how illness has affected them. It offers a model for improving health outcomes. To determine whether incorporating a narrative approach in patients with cancer decreases pain intensity and improves their global sense of well-being, we performed a randomized, single-blind controlled trial in adult patients with cancer and average pain intensity levels of at least 5/10. Two hundred thirty-four patients were randomized into three groups: (1) narrative (n=79), in which patients wrote a story about how cancer affected their lives for at least 20 minutes once a week for three weeks; (2) questionnaire (n=77), in which patients filled out the McGill Pain Questionnaire; and (3) control (n=78), in which patients came weekly to medical visits during which they received usual customary care. Patients rated their pain on a 0-10 scale and their well-being on a seven-point Likert scale weekly for eight weeks. Two raters independently evaluated the emotional content of the narratives. Pain intensity and sense of well-being were similar in all groups before and after treatment. Subgroup analyses showed that patients whose narratives had high emotional disclosure had significantly less pain and reported higher well-being scores than patients whose narratives were less emotional. Further study is needed to demonstrate whether the implementation of narrative medicine is associated with health benefits in this and other contexts.

Adjusting the pH of lidocaine for reducing pain on injection

BACKGROUND

Lidocaine administration produces pain due to its acidic pH.

OBJECTIVES

The objective of this review was to determine if adjusting the pH of lidocaine had any effect on pain resulting from non-intravascular injections in adults and children. We tested the hypothesis that adjusting the pH of lidocaine solution to a level closer to the physiologic pH reduces this pain.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, to June 2010); Ovid MEDLINE (1966 to June 2010); EMBASE (1988 to June 2010); LILACS (1982 to June 2010); CINAHL (1982 to June 2010); ISI Web of Science (1999 to June 2010); and abstracts of the meetings of the American Society of Anesthesiologists (ASA). We checked the full articles of selected titles. We did not apply any language restrictions.

SELECTION CRITERIA

We included double-blinded, randomized controlled trials that compared pH-adjusted lidocaine with unadjusted lidocaine. We evaluated pain at the injection site, satisfaction and adverse events. We excluded studies in healthy volunteers.

DATA COLLECTION AND ANALYSIS

We separately analysed parallel-group and crossover trials; trials that evaluated lidocaine with or without epinephrine; and trials with pH-adjusted lidocaine solutions < 7.35 and ≥ 7.35. To explain heterogeneity, we separately analysed studies with a low and higher risk of bias due to the level of allocation concealment; studies that employed a low and a higher volume of injection; and studies that used lidocaine for different types of procedures.

MAIN RESULTS

We included 23 studies of which 10 had a parallel design and 13 were crossover studies. Eight of the 23 studies had moderate to high risk of bias due to the level of allocation concealment.Pain associated with the infiltration of buffered lidocaine was less than the pain associated with infiltration of unbuffered lidocaine in both parallel and crossover trials. In the crossover studies, the difference was -1.98 units (95% confidence interval (CI) -2.62 to -1.34) and in the parallel-group studies it was -0.98 units (95% CI -1.49 to -0.47) on a 0 to 10 scale. The magnitude of the pain decrease associated with buffered lidocaine was larger when the solution contained epinephrine. The risk of bias, volume of injection, and type of procedure failed to explain the heterogeneity of the results.Patients preferred buffered lidocaine (odds ratio 3.01, 95% CI 2.19 to 4.15). No adverse events or toxicity were reported.

AUTHORS' CONCLUSIONS

Increasing the pH of lidocaine decreased pain on injection and augmented patient comfort and satisfaction.

Microbiome-Gut-Brain Axis: Probiotics and Their Association With Depression

To assess the association of probiotics with depression, a large population-based cross-sectional study was conducted. National Health and Nutrition Examination Survey adult participants from 2005 through 2012 were included. Exposure was defined as having consumed any probiotic food or supplement on any of the interview days. Subjects were classified as depressed if Patient Health Questionnaire scores were ≥10. Of the 18,019 subjects included, 14.11% consumed probiotics. Unadjusted analysis suggested that subjects who consumed probiotics had lower odds of depression (OR=0.58, 95% CI=0.45-0.75). After adjustment for characteristics associated with depression and probiotic exposure, the effect was attenuated (OR=0.82, 95% CI=0.61-1.1) and no longer significant. Use of probiotics is not associated with lower rates of depression in this national sample.

Depression Is Associated With High Levels of C-Reactive Protein and Low Levels of Fractional Exhaled Nitric Oxide: Results From the 2007-2012 National Health and Nutrition Examination Surveys

OBJECTIVE

Major depressive disorder may be due to psychoneuroimmunological dysfunction, as studies have documented increased levels of a variety of inflammatory mediators in depressed subjects. Nitric oxide (NO) is marker of inflammation, and fractional exhaled NO (FeNO) is a marker of airway inflammation. Plasma NO and FeNO levels have been shown to be lower in subjects with depression in small studies. We sought to assess the association of depression with C-reactive protein (CRP) and FeNO levels in a large and representative sample of the US population.

METHODS

Population-based cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES). NHANES collects health information about the US population through interviews, medical examinations, and laboratory tests. We included subjects ≥ 20 years old who participated in NHANES in 2007 to 2012, responded to the depression questions, and had CRP values or ≥ 2 reproducible FeNO measures. Depression was measured using the 9-item Patient Health Questionnaire (PHQ-9). Subjects were classified as depressed if PHQ-9 scores were ≥ 10. FeNO and CRP levels were log transformed. Unadjusted and adjusted regression analyses were conducted.

RESULTS

A total of 14,276 subjects responded to the PHQ-9, and 7.73% had depressive symptoms. Of these subjects, 10,036 had CRP values and 12,513 had FeNO measurements. Subjects with depressive symptoms had, after adjustment, CRP levels that were 31% higher (95% confidence interval [CI], 14% to 50%) and FeNO levels that were 10.7% lower (95% CI, -2.5% to -17.1%) than in subjects with no depressive symptoms.

CONCLUSIONS

Depression is associated with high CRP levels and low FeNO levels. Of importance, this study (1) assesses the association of depression with CRP and exhaled NO levels in a large and representative sample of the US population, (2) contributes to the neuroimmunological dimension of depression, (3) confirms the association of depression with high levels of CRP, and (4) assesses, for the first time, the association of depression with peripheral NO in more than 10,000 subjects from the general population.

Local anesthetic sympathetic blockade for complex regional pain syndrome

BACKGROUND

Local anesthetic blockade of the sympathetic chain is widely used to treat reflex sympathetic dystrophy (RSD) and causalgia. These two pain syndromes are now conceptualized as variants of a single entity: complex regional pain syndrome (CRPS). A recent meta-analysis of the topic has been published. However, this study only evaluated studies in English language and therefore it could have overlooked some randomized controlled trials.

OBJECTIVES

This systematic review had three objectives: to determine the likelihood of pain alleviation after sympathetic blockade with local anesthetics in the patient with CRPS; to assess how long any benefit persists; and to evaluate the incidence of adverse effects of the procedure.

SEARCH STRATEGY

We searched the Cochrane Pain, Palliative and Supportive Care Register, the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, LILACS, and conference abstracts of the World Congresses of the International Association for the Study of Pain. Bibliographies from retrieved articles were also searched for additional studies.

SELECTION CRITERIA

We considered for inclusion randomized controlled trials that evaluated the effect of sympathetic blockade with local anesthetics in children or in adult patients to treat RSD, causalgia, or CRPS.

DATA COLLECTION AND ANALYSIS

The outcomes of interest were the number of patients who obtained at least 50% of pain relief shortly after sympathetic blockade (30 minutes to 2 hours) and 48 hours or later. We also assessed the presence of adverse effects in each treatment arm. A random effects model was used to combine the studies.

MAIN RESULTS

Two small randomized double blind cross over studies that evaluated 23 subjects were found. The combined effect of the two trials produced a relative risk (RR) to achieve at least 50% of pain relief 30 minutes to 2 hours after the sympathetic blockade of 1.17 (95% CI 0.80-1.72). It was not possible to determine the effect of sympathetic blockade on long-term pain relief because the authors of the two studies evaluated different outcomes.

AUTHORS' CONCLUSIONS

This systematic review revealed the scarcity of published evidence to support the use of local anesthetic sympathetic blockade as the 'gold standard' treatment for CRPS. The two randomized studies that met inclusion criteria had very small sample sizes, therefore, no conclusion concerning the effectiveness of this procedure could be drawn. There is a need to conduct randomized controlled trials to address the value of sympathetic blockade with local anesthetic for the treatment of CRPS.

Antifibrinolytic agents for reducing blood loss in scoliosis surgery in children

BACKGROUND

Scoliosis surgery is often associated with substantial blood loss and potential detrimental effects in children. Antifibrinolytic agents are often used to reduce perioperative blood loss. Clinical trials have evaluated their effect in children undergoing surgical correction of scoliosis but no systematic review has been published. We performed a systematic review on the efficacy and safety of antifibrinolytic drugs in children undergoing scoliosis surgery.

OBJECTIVES

To assess the efficacy and safety of aprotinin, tranexamic acid and aminocaproic acid in reducing blood loss and transfusion requirements in children undergoing scoliosis surgery.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2007, Issue 3), OVID MEDLINE (1950 to September 3rd 2007), LILACS (1992 to June 20th 2007) and EMBASE (1980 to July 23rd 2007). We also searched conference proceedings from 2003 to 2007 and the clinicaltrials.gov registry. No language restriction was applied.

SELECTION CRITERIA

We included blinded or unblinded randomized controlled trials that evaluated the effect of antifibrinolytics on perioperative blood loss in children that were 18 years of age or younger and undergoing scoliosis surgery.

DATA COLLECTION AND ANALYSIS

Two authors independently performed the data extraction. Primary outcomes were mortality and number of patients transfused. Secondary outcomes were number of patients transfused with allogeneic blood, amount of total blood transfused, total blood loss and adverse events. To assess heterogeneity we used the I(2) test and for the quantitative analysis we used a fixed-effect model.

MAIN RESULTS

Six studies fulfilled the inclusion criteria. The total number of participants was 254, of whom 127 were allocated to placebo and 127 to antifibrinolytic drugs. Aprotinin, tranexamic acid and aminocaproic acid were evaluated in two studies each. All studies had placebo as the control group intervention. There were no deaths or any serious adverse events in any study, in either the active or the control group. The risk of being transfused was similar in patients receiving antifibrinolytic drugs or placebo. Antifibrinolytics drugs decreased the amount of blood transfused by 327 ml (95% CI -469.04 to -185.78) and the amount of blood loss by 427 ml (95% CI -602.51 to -250.56). There was no indication of publication bias, however, we cannot rule it out due to the small number of studies included.

AUTHORS' CONCLUSIONS

The effect of antifibrinolytic drugs on mortality could not be assessed. Antifibrinolytic drugs reduced blood loss and the amount of blood transfused in children undergoing scoliosis surgery; however, their effect on the number of children requiring blood transfusion remains unclear. Aprotinin, tranexamic acid and aminocaproic acid seem to be similarly effective.

Finding factors that predict treatment-resistant depression: Results of a cohort study

BACKGROUND

Treatment for depressive disorders often requires subsequent interventions. Patients who do not respond to antidepressants have treatment-resistant depression (TRD). Predicting who will develop TRD may help healthcare providers make more effective treatment decisions. We sought to identify factors that predict TRD in a real-world setting using claims databases.

METHODS

A retrospective cohort study was conducted in a US claims database of adult subjects with newly diagnosed and treated depression with no mania, dementia, and psychosis. The index date was the date of antidepressant dispensing. The outcome was TRD, defined as having at least three distinct antidepressants or one antidepressant and one antipsychotic within 1 year after the index date. Predictors were age, gender, medical conditions, medications, and procedures 1 year before the index date.

RESULTS

Of 230,801 included patients, 10.4% developed TRD within 1 year. TRD patients at baseline were younger; 10.87% were between 18 and 19 years old versus 7.64% in the no-TRD group, risk ratio (RR) = 1.42 (95% confidence interval [CI] 1.37-1.48). TRD patients were more likely to have an anxiety disorder at baseline than non-TRD patients, RR = 1.38 (95% CI 1.35-1.14). At 3.68, fatigue had the highest RR (95% CI 3.18-4.25). TRD patients had substance use disorders, psychiatric conditions, insomnia, and pain more often at baseline than non-TRD patients.

CONCLUSION

Ten percent of subjects newly diagnosed and treated for depression developed TRD within a year. They were younger and suffered more frequently from fatigue, substance use disorders, anxiety, psychiatric conditions, insomnia, and pain than non-TRD patients.

Music does not reduce alfentanil requirement during patient-controlled analgesia (PCA) use in extracorporeal shock wave lithotripsy for renal stones

To evaluate the impact of music on opioid requirements and pain levels during renal lithotripsy using alfentanil patient-controlled analgesia (PCA), we conducted a prospective, blinded, randomized controlled trial. Patients undergoing lithotripsy were instructed in PCA use and asked to rate their anxiety and select their preferred type of music. They were then premedicated with morphine and ketorolac and randomly allocated into two groups. Group 1 (n = 97) had music started 10 min before the procedure and maintained until 10 min after its conclusion. Group 2 (n = 96) had music begun at the conclusion of lithotripsy and continued for 10 min. Pain intensity, alfentanil requirement, side effects, quality of analgesia, patient satisfaction, and acceptance of the technique were evaluated. Demographics, alfentanil requirement, pain levels, side effects, quality of analgesia, and patient satisfaction were similar in both groups. The addition of music did not provide any benefit. This result raises the possibility that some nonpharmacologic therapies have minimal impact in settings where the painful stimulus is moderate to severe and adequate pharmacotherapy is available.

High-performance liquid chromatographic determination of morphine and its 3- and 6-glucuronide metabolites by two-step solid-phase extraction

To provide more accurate measurement of morphine and its metabolites for a study of the genetic differences on morphine response, a method for the analysis of morphine and its metabolites is described which has the advantages of increased sensitivity and specificity by using a cleaner extraction. The new extraction method involves both the hydrophobic isolation on a carbon cartridge and ion-exchange isolation on ion-exchange resin which has not preliminary been described for morphine analysis. The combination of these two steps successfully purified drugs from human plasma with maximum removal of interfering substance comparing with a conventional C18 cartridge alone. The analytes are quantified by high-performance liquid chromatography on a reversed-phase C18 column employing a mobile phase consisting of 25% acetonitrile in 0.05 M phosphate buffer (pH 2.1), and 2.5 mM sodium dodecyl sulfate as the pairing ion with a combination of electrochemical and fluorometric detections. The recoveries for morphine (M), morphine-3-glucuronide (M3G), morphine-6-glucuronide (M6G) and hydromorphone after the SPE procedure were 86+/-7.1%, 82+/-6.9%, 79+/-6.0% and 85+/-6.0%, respectively. Limits of detection for this method are 0.1 ng/ml for M, and 0.18 ng/ml for M3G and M6G. Limits of quantitation were approximately 0.25 ng/ml for M, and 0.45 ng/ml for M3G and M6G. The present assay was applied to measure M, M3G and M6G content in human plasma to test the applicability and suitability of this method for clinical and research use.

Association of flossing/inter-dental cleaning and periodontitis in adults

Aim

Assess the association of flossing with periodontitis.

Materials and Methods

This was a cross‐sectional study using the National Health and Nutrition Examination Survey (NHANES) years 2011‐2014. We used three categories of flossing: 0–1, 2–4 and ≥5 days in the past week and the CDC definition of periodontitis. We calculated odds ratios controlling for age, gender, smoking, drinking, income and dentist visits.

Results

A total of 6939 adult subjects were included, 35% flossed ≤1 time a week, and 40% had periodontitis. After adjustment, the odds of periodontitis were 17% lower for subjects who flossed >1 time a week than for subjects who flossed less often (odds ratio=0.83, 95% CI 0.72–0.97). A dose response was not observed. Men were twice as likely as women to have periodontitis. Younger subjects, non‐smokers and subjects with the highest incomes had lower odds of having periodontitis.

Conclusions

Flossing was associated with a modestly lower prevalence of periodontitis. Older age, being male, smoking, low income and less frequent dental visits were associated with a higher prevalence of periodontitis. Flossing 2–4 days a week could be as beneficial as flossing more frequently. This is a cross‐sectional study so a causal relation between flossing and periodontitis cannot be established.

Analgesic activity of a novel bivalent opioid peptide compared to morphine via different routes of administration

A novel bivalent opioid tetrapeptide, biphalin (Tyr-D-Ala-Gly-Phe-NH)2, was synthesized based on structure-activity relationships. The analgesic activity of biphalin was assessed in comparison to morphine in rats. Drugs were administered subcutaneously (s.c.), intravenously (i.v.) and intrathecally (i.t.). Tail flick and tail pinch were used as tests for analgesia. Biphalin s.c. showed negligible analgesic activity, but when given i.v. produced significant analgesia, although less potent than morphine via this route. In contrast, intrathecal biphalin was more potent than morphine. These results indicate that biphalin has intrinsic activity that is compromised by enzymatic degradation or redistribution in the periphery, properties that may render it useful in exploring analgesic actions of locally applied opioids in the periphery without the likelihood of unwanted central effects.