CA5-02: Assessing the Performance of Propensity Score Methods for Estimating the Probability of Receiving Cervical Procedures

Background/Aims Propensity scores provide an alternative to traditional regression modeling for assessing the effect of exposure on an outcome in the presence of confounders. We describe methods to establish propensity scores for a cohort of Kaiser Permanente Northwest (KPNW) members receiving surgical procedures of the cervix. Methods The HMORN Virtual Data Warehouse (VDW) was used to obtain health plan enrollment, diagnosis, procedure, and demographic data for a cohort of 14- to 53-year-old KPNW women during the study years, 1998-2009. Unexposed women were matched to exposed women on age and calendar year. We performed logistic regression to model the propensity of receiving surgical procedures of the cervix. Potential covariates included smoking status, race and ethnicity, sexually transmitted infections (STI), immunocompromised status, length of health plan enrollment, and number of encounters per enrollment year. Propensity score balance was assessed using histograms and boxplots. The common support condition was imposed. Matching on propensity scores was performed using a greedy 5 to 1 digit match. Results There were 86,898 women in our cohort. Women receiving a surgical procedure were more likely to be current tobacco users, immunocompromised, have a history of STI, have longer prior enrolment in the health plan, and have more healthcare encounters per enrolment year than unexposed women. In our cohort, propensity scores for receiving invasive cervical procedures for exposed women ranged from 0.02 to 0.56 (n=4138; mean=0.08; median=0.06), whereas propensity scores for unexposed women ranged from 0.01 to 0.99 (n=82760; mean=0.05; median=0.04). We excluded 1,819 (2%) unexposed women based on the common support condition. A 1:3 match ratio produced the best matched population. No matches were found for 43 (1%) of our exposed population. Discussion Use of the HMORN VDW enabled us to create propensity scores for estimating the probability of receiving cervical procedures. Matching and imposing the common support condition decreased our study population minimally. However, women excluded from analysis may be intrinsically different from those who remained. One limitation to our study is that some potential variables we wished to include in our model, such as marital status, were not available in HMORN VDW data which may introduce bias.     

Prospective validation of risk prediction indexes for acute and delayed chemotherapy-induced nausea and vomiting

Background

Despite the use of standardized anti-emetic guidelines, up to 20% of cancer patients suffer from moderate-to-severe chemotherapy-induced nausea and vomiting (cinv)—that is, grade 2 or greater according to the U.S. National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. We previously developed cycle-based prediction models and associated scoring systems for acute and delayed cinv. As part of the validation process, we prospectively evaluated the ability of the scoring systems to accurately identify patients deemed to be high risk for grade 2 or greater cinv.

Methods

Patients who were receiving any chemotherapy for solid tumours and who consented to participate were provided with symptom diaries. Compliance to the diaries was enhanced by 24-hour and 5-day telephone callbacks after chemotherapy in every cycle. All patients received anti-emetic prophylaxis as prescribed by the treating physician. Before each cycle of chemotherapy, the acute and delayed cinv scoring systems were used to stratify patients into low- and high-risk groups. Logistic regression modelling was then applied to compare the risk for grade 2 or greater cinv between patients considered to be at high and at low risk. The external validity of each system was also assessed using an area under the receiver operating characteristic curve (auroc) analysis.

Results

We collected cinv outcomes data from 95 patients during 181 cycles of chemotherapy. The incidence of grade 2 or greater acute and delayed cinv was 17.7% and 18.2% respectively. As previously identified, major predictors for grade 2 or greater cinv included younger patient age, platinum- or anthracycline-based chemotherapy, low alcohol consumption, earlier cycles of chemotherapy, previous history of morning sickness, and prior emetic episodes after chemotherapy. The acute and delayed scoring systems both had good predictive accuracy when applied to the external validation sample (acute—auroc: 0.69; 95% confidence interval: 0.59 to 0.79; delayed—auroc: 0.70; 95% confidence interval: 0.60 to 0.80). Patients identified by the scoring systems to be at high risk were 2.8 (p = 0.025) and 3.1 (p = 0.001) times more likely to develop grade 2 or greater acute and delayed cinv.

Conclusions

The present study demonstrates that our scoring systems are able to accurately identify patients at high risk for acute and delayed cinv. Application and planned continued refinement of the scoring systems will be an important means of patient-specific risk assessment that will allow for optimization of anti-emetic therapy.     

A randomized controlled trial of sucrose and/or pacifier as analgesia for infants receiving venipuncture in a pediatric emergency department

Background  

Although sucrose has been accepted as an effective analgesic agent for procedural pain in neonates, previous studies are largely in the NICU population using the procedure of heel lance. This is the first report of the effect of sucrose, pacifier or the combination thereof for the procedural pain of venipuncture in infants in the pediatric emergency department population.     

Contributors to primary care guidelines: What are their professions and how many of them have conflicts of interest?

Objective

To determine the professions of those who contribute to guidelines, guideline variables associated with differing contributor participation, and whether conflict of interest statements are provided in primary care guidelines.

Design

Retrospective analysis of the primary care guidelines from the Canadian Medical Association website. Two independent data extractors reviewed the guidelines and extracted relevant data.

Setting

Canada.

Main outcome measures

Sponsors of guidelines, jurisdiction (national or provincial) of guidelines, the professions of those who contribute to guidelines, and the reported conflict of interest statements within guidelines.

Results

Of the 296 guidelines in the family medicine section of the CMA Infobase, 65 were duplicates and 35 had limited relevance to family medicine. Twenty did not provide contributor information, leaving 176 guidelines for analysis. In total, there were 2495 contributors (authors and committee members): 1343 (53.8%) non–family physician specialists, 423 (17.0%) family physicians, 141 (5.7%) nurses, 75 (3.0%) pharmacists, 269 (10.8%) other clinicians, 203 (8.1%) nonclinician scientists, and 41 (1.6%) unknown professions. The proportion of contributors from the various professions differed significantly between provincial and national guidelines, as well as between industry-funded and non–industry-funded guidelines (both P < .001). For provincial guidelines, 30.8% of contributors were family physicians and 37.3% were other specialists compared with 13.9% and 57.4%, respectively, for national guidelines. Of industry-funded guidelines, 7.8% of contributors were family physicians and 68.6% were other specialists compared with 19.4% and 49.9%, respectively, for non–industry-funded guidelines. Conflicts of interest were not reported in 68.9% of guidelines. When reported, conflict of interest statements were present for 48.6% of non–family physician specialists, 30.0% of pharmacists, 27.7% of family physicians, and 10.0% or less of the remaining groups; differences were statistically significant (P < .001).

Conclusion

Non–family physician specialists outnumber all other health care providers combined and are more than 3 times more likely to contribute to primary care guidelines than family physicians are. Conflict of interest statements were provided in the minority of guidelines, and for guidelines in which conflict of interest statements were included, non–family physician specialists were most likely to report them. Guidelines targeted to primary care should have much more primary care and family medicine representation and include fewer contributors who have conflicts of interest.Following guidelines is often promoted as the standard of care, and guideline recommendations are used to define performance measures. However, adoption of guidelines into primary care is frequently seen as suboptimal.^1–3 The reasons behind this are likely multi-factorial. Reasons include patient factors such as lack of adherence,³ guideline factors such as the surrogate-marker targets that are unattainable despite administration of evidence-based therapies,^1,2 and physician factors such as lack of treatment intensification.³The reasons why physicians might be reluctant to embrace guidelines are also likely multifactorial. Approximately 50% of guideline recommendations are based only on the lowest level of evidence or expert opinion.^4,5 Furthermore, it appears that review and interpretation of the literature by clinical experts is at risk of bias, and the more specialized the expert the higher the risk of bias.⁶ Additionally, one study found that conflicts of interest were present for approximately 50% of guideline contributors in the United States and Canada; however, this research was based on only 14 guidelines.⁷Most care takes place in primary care settings,⁸ and 93% of patients identify their primary care doctors as their usual physicians.⁹ The average 65-year-old patient presenting to primary care has 6 chronic medical conditions,¹⁰ meaning the single-disease focused nature of guidelines might translate poorly into practice.^11,12 Moreover, only 0.1% of guideline content promotes shared decision making.¹³ Finally, recommendations in guidelines for which family physicians are contributors might differ from recommendations in guidelines for which family physicians are not contributors.¹⁴Two issues appear to be colliding. Family physicians and primary care providers have unique clinical perspectives and provide most patient care. However, clinical experts appear to provide a large portion of the recommendations in primary care guidelines and their opinions might be biased. New standards from the Institute of Medicine indicate that there should be balance of professions among guideline contributors and, whenever possible, contributors should not have conflicts of interest.¹⁵ Our primary objective was to determine the professional designation of contributors to primary care guidelines in Canada. Our secondary objectives included determining guideline characteristics that might influence the relative proportion of different professions, as well as whether conflicts of interest were reported in the guidelines and by the contributors.     

Efficacy of supplemental peripheral nerve blockade for hip fracture surgery: multiple treatment comparison

Purpose

This study was designed to determine the most effective peripheral nerve block supplement to standard anesthesia management for hip fracture patients.

Methods

We systematically reviewed randomized controlled trials (RCTs) published from 1990 to 2010 and conducted multiple treatment comparisons using direct and indirect evidence for two outcomes, i.e., acute pain intensity and delirium. We combined trials by type of injection (regardless of time of insertion during the perioperative phase, use of nerve block catheter, local anesthetic type, additives, or duration of treatment).

Results

Twenty-one RCTs comprising 1,422 participants were included. In most cases, the trials were conducted in Europe; they excluded patients with cognitive impairment, and they were unclear or at high risk of bias. The combination of obturator and lateral femoral cutaneous nerve blockade had the highest probability of being the most effective against acute postoperative pain. Fascia iliaca blockade had the highest probability of being the most effective against delirium. There was no difference in outcomes among other nerve blocks.

Conclusion

Not all nerve blocks are equally effective in improving outcomes after hip fracture. Multiple treatment comparison, a tool to compare the effectiveness of multiple treatments simultaneously, provides useful guidance to anesthesia providers seeking effective treatment when faced with a body of RCTs wherein each investigates one treatment. More RCTs comparing multiple nerve blocks in hip fracture are needed.