Propensity Score Matching Methodology Research Articles

Burden of constipation-predominant irritable bowel syndrome (IBS-C) in France, Italy, and the United Kingdom

BackgroundSeveral studies have examined the effect of irritable bowel syndrome (IBS) on health outcomes in Western Europe, but less research has focused on the constipation subtype (IBS-C). The current study addresses this gap by comparing patients with IBS-C and matched controls for health status, work productivity, and resource utilization.MethodsData were obtained from the 2010 5EU National Health and Wellness Survey (NHWS), which includes respondents from France, Germany, Italy, Spain, and the UK. Only participants from France (n = 15,051), Italy (n = 7580), and the UK (n = 15,065) were included in the analyses. Respondents who reported a physician diagnosis of IBS and reported only constipation symptoms were compared with respondents who did not report being diagnosed with IBS using a propensity score-matching methodology (matching on sociodemographics, health behaviors, and comorbidities). Differences between patients with IBS-C and matched controls were examined on health status (Short Form Survey Instrument version 2), work productivity (Work Productivity and Activity Impairment questionnaire), and health care resource use in the past 6 months.ResultsA total of 83 (0.55%), 109 (1.44%), and 204 (1.35%) respondents reported a diagnosis of IBS with only constipation symptoms in France, Italy, and the UK, respectively. Within each country, patients with IBS-C reported significantly worse health status compared with matched controls (all P < 0.05) and significantly more physician visits (all P < 0.05). More hospitalizations were also observed in the UK (P < 0.05). Among those who were employed, patients with IBS-C in France and the UK also reported significantly more presenteeism than matched controls (all P < 0.05).ConclusionThese findings highlight the pervasive influence of IBS-C on the day-to-day functioning of sufferers, their ability to be productive at work, and their influence on the wider health care system. Significant unmet needs remain, and improved management of this condition could result in significant and clinically meaningful gains in health status as well as alleviating a societal cost burden.

Prognosis of patients with multifocal glioblastoma: a case-control study

The prognosis of patients with glioblastoma who present with multifocal disease is not well documented. The objective of this study was to determine whether multifocal disease on initial presentation is associated with worse survival. The authors retrospectively reviewed records of 368 patients with newly diagnosed glioblastoma and identified 47 patients with multifocal tumors. Each patient with a multifocal tumor was then matched with a patient with a solitary glioblastoma on the basis of age, Karnofsky Performance Scale (KPS) score, and extent of resection, using a propensity score matching methodology. Radiation and temozolomide treatments were also well matched between the 2 cohorts. Kaplan-Meier estimates and log-rank tests were used to compare patient survival. The incidence of multifocal tumors was 12.8% (47/368). The median age of patients with multifocal tumors was 61 years, 76.6% had KPS scores ≥ 70, and 87.2% underwent either a biopsy or partial resection of their tumors. The 47 patients with multifocal tumors were almost perfectly matched on the basis of age (p = 0.97), extent of resection (p = 1.0), and KPS score (p = 0.80) compared with 47 patients with a solitary glioblastoma. Age (>65 years), partial resection or biopsy, and low KPS score (<70) were associated with worse median survival within the multifocal group. In the multifocal group, 19 patients experienced tumor progression on postradiation therapy MRI, compared with 11 patients (26.8%) with tumor progression in the unifocal group (p = 0.08). Patients with multifocal tumors experienced a significantly shorter median overall survival of 6 months (95% CI 4-10 months), compared with the 11-month median survival (95% CI 10-19 months) of the matched solitary glioblastoma group (p = 0.02, log-rank test). Two-year survival rates were 4.3% for patients with multifocal tumors and 29.0% for the unifocal cohort. Patients with newly diagnosed multifocal tumors were found to have an almost 2-fold increase in the hazard of death compared with patients with solitary glioblastoma (hazard ratio 1.8, 95% CI 1.1-3.1; p = 0.02). Tumor samples were analyzed for expression of phosphorylated mitogen-activated protein kinase, phosphatase and tensin homolog, O(6)-methylguanine-DNA methyltransferase, laminin β1 and β2, as well as epidermal growth factor receptor amplification, and no significant differences in expression profile between the multifocal and solitary glioblastoma groups was found. Patients with newly diagnosed multifocal glioblastoma on presentation experience significantly worse survival than patients with solitary glioblastoma. Patients with multifocal tumors continue to pose a therapeutic challenge in the temozolomide era and magnify the challenges faced while treating patients with malignant gliomas.

Gender differences in the effects of prison on recidivism

PurposeThis study examines gender differences in the effectiveness of prison in reducing recidivism. MethodsUsing data on released male and female prisoners, we apply a propensity score matching methodology to compare the effects of prison on recidivism versus three counterfactual conditions—jail, intensive probation, and probation. ResultsThe analyses indicated that a prison term, as compared to placement on intensive probation or traditional probation, is associated with a greater likelihood of property and drug recidivism. There was little evidence that recidivism was greater when compared to jail, that prison increased the likelihood of violent or other recidivism, or that the criminogenic effect of prison is appreciably greater for females or males. ConclusionsThe findings do not support arguments that prison is an effective alternative to non-incarcerative punishments or that it exerts a differential effect on females or males. Further research is needed on what features of the prison experience contribute to the observed effects.

Real effects of private equity investments: Evidence from European buyouts

This study investigates the effects of buyout deals on the ex-post performance of target companies. The analysis is based on a sample of 241 private-to-private buyouts involving European companies between 1997 and 2004 and a control sample of non-buyouts selected through a propensity score matching methodology. The paper explores three different dimensions of firm performance: size, profitability and productivity. The results indicate a positive impact of buyouts on the growth of total assets and of employment in target firms in the short- and mid-term. An equivalent clear pattern cannot be identified for productivity, while we estimate a lower operating profitability for buyout companies with respect to the control group three years after a deal is made. When we restrict the analysis to the sub-sample of buyout companies, we find that generalist funds negatively and significantly impact the mean ex-post operating profitability of PE-backed firms, while turnaround specialists are positively associated with operating profitability. The evidence also highlights that target companies whose lead investor is located in the same country show relatively higher ex-post profitability performance.

OVERDRAFT FACILITY POLICY AND FIRM'S PERFORMANCE: AN EMPIRICAL ANALYSIS IN EASTERN EUROPEAN UNION INDUSTRIAL FIRMS

This article evaluates the effect of the overdraft facility (or line of credit) policy by comparing a large sample of overdraft facilitated firms and matched non-overdraft facilitated firms from Eastern Europe at sector level. The sample firms are compared with respect to rates of different performance indicators including: technical efficiency (a Data Envelopment Analysis – DEA – approach is applied to estimate technical efficiency level for individual sectors), production workers trained, expenditures of R&amp;D, and export activity. In order to avoid the selectivity problem, propensity score matching methodologies are adopted. Results suggest that a certain level of overdraft facility given to a firm would be needed to stimulate investment in R&amp;D, which will eventually result in growth in productivity.

Adoption of inflation targeting and tax revenue performance in emerging market economies: An empirical investigation

This paper investigates whether the adoption of inflation targeting (IT), by strengthening central bank independence and maintaining inflation at low levels, has encouraged the governments of emerging economies to improve the collection of domestic tax revenue in order to recoup the loss of seigniorage revenue. Using the propensity score matching methodology, a micro-econometric methodology recently used in macroeconomics, we evaluate the ‘treatment effect’ of IT on fiscal mobilization in emerging countries that have adopted this monetary policy framework. Our empirical analysis, conducted on a sample of 59 countries (19 IT and 40 non-IT countries) for the period from 1980 to 2009, shows that on average IT adoption has had a large and significant positive effect on public revenue collection. Our results are confirmed by extensive robustness tests.

Investments, Financing Constraints and Buyouts: The Effect of Private Equity Investors on the Sensitivity of Investments to Cash Flow

The paper examines the relationship between investments and cash flows for a panel of 204 low- and medium-technology firms located in the UK, France, Italy and Spain, 108 of which underwent a buyout between 1997 and 2004. The control sample of non-buyouts is selected through a propensity score matching methodology. I investigate whether, after firms obtain PE financing in buyout transactions, their investment rates are both lower and more sensitive to cash flows. In addition, I analyze the effect exerted by the characteristics of the deal and the investing funds. I compare results from countries belonging to different legal systems and exhibiting different levels of development of the private equity industry (English versus French legal origin countries). The results highlight that the sensitivity of investments to cash flows is increased if firms obtain equity financing from PE investors, while investment levels do not seem to be affected after a buyout However, differential effects emerge when considering the framework conditions in which investee firms operate and the typology and characteristics of investing funds.

Effect of Gender on Prehospital Refusal of Medical Aid

Background“Refusal of medical aid” (RMA) is the term commonly used by emergency medical technicians (EMTs) when someone calls 911 for care (usually the patient or a family member) but, after the initial encounter with the EMTs, the patient refuses emergency medical services transport to the hospital. Some intervention may have been performed, such as taking vital signs or an electrocardiogram, before the RMA. Although there have been multiple studies of the characteristics and outcomes of patients who RMA, little analysis has been done of the role of EMTs in these cases. ObjectiveTo analyze the association between EMT gender and the patient’s decision to refuse medical aid in the prehospital setting. MethodsThe study was performed using data from one hospital-based ambulance service in an urban setting that participates in the 911 system. This was a case control study that examined the data from consecutive patients who refused medical aid for a 1-year period compared to a control group of non-RMA patients. ResultsThere was a significantly higher representation of all-male EMT teams in the RMA group (p<0.0001). Using propensity score-matching methodology to control for other factors, all-male EMT teams were 4.75 times more likely to generate an RMA as compared to all-female and mixed-gender EMT teams (95% confidence interval 1.63–13.96, p=0.0046). ConclusionWe found that the gender of the EMTs was one of the most important factors associated with RMA, with a much higher frequency of RMAs occurring when both members of the team were male.

Is inflation targeting a good remedy to control inflation?

Since the 1990s inflation targeting (IT) has been adopted by several central banks as a strategy for monetary policy. It is expected that the adoption of this monetary regime can reduce inflation and inflation volatility. This article is concerned with these issues and makes use of the Propensity Score Matching methodology on a sample of 180 countries for the period from 1990 to 2007. For analysis, the sample is split into two sets of countries (advanced and developing). The findings suggest that the adoption of IT is an ideal monetary regime for developing economies and, in addition to reducing inflation volatility, can drive inflation down to internationally acceptable levels. Regarding advanced economies, the adoption of IT does not appear to represent an advantageous strategy. In brief, the empirical results indicate that the adoption of IT is useful for countries that must enhance their credibility for the management of monetary policy.

Evaluating the Impact of Public Subsidies on a Firm's Performance: A Quasi-Experimental Approach

Abstract: Many regional governments in developed countries design programs to improve the competitiveness of local firms. In this paper, we evaluate the effectiveness of public programs whose aim is to enhance the performance of firms located in Catalonia (Spain). We compare the performance of publicly subsidised companies (treated) with that of similar, but unsubsidised companies (non-treated). We use the Propensity Score Matching (PSM) methodology to construct a control group which, with respect to its observable characteristics, is as similar as possible to the treated group, and that allows us to identify firms which retain the same propensity to receive public subsidies. Once a valid comparison group has been established, we compare the respective performance of each firm. As a result, we find that recipient firms, on average, change their business practices, improve their performance, and increase their value added as a direct result of public subsidy programs.

Evaluating the effects of equity incentives using PSM: Evidence from China

This paper investigates the effects of equity incentives on firm performance in Chinese listed firms. We address the sample selection problem by employing the propensity score matching methodology. Results show that, (1) On the whole, performance is positively related to equity incentives even after controlling for sample selection bias; (2) The final control rights have an important impact on the effects of equity incentives. The execution of equity incentives in privately owned firms can significantly decrease the agency costs between shareholders and managers, but such effects cannot be observed in state-owned firms; (3) Effects of equity incentives depend on the incentive type, that is, comparing to stock-based incentives, option-based incentives can reduce the agency costs significantly, thus are more effective; (4) Ownership structure also has important impacts on the effects of equity incentives. The agency costs decrease in firms with more decentralized ownership after introducing equity incentive, while in concentrated firms the effect is negligible.

Impacto da redução dos encargos trabalhistas sobre a formalização das empregadas domésticas

Este artigo analisa o impacto da redução dos encargos trabalhistas (previstos na lei 11.324 de julho 2006) sobre a formalização das empregadas domésticas. Para a construção do grupo de controle foi adotada a metodologia de pareamento por escore de propensão e para estimar o efeito causal da lei sobre a formalização utilizou-se o estimador de diferenças-em-diferenças. Foram utilizados dados da Pesquisa Mensal de Emprego/IBGE dos anos de 2004 a 2007 e os resultados indicam um efeito inconclusivo da lei sobre a formalização, pois algumas estimativas mostraram efeitos positivos enquanto outras não foram significativas.

Can Marriage Reduce Risky Health Behavior for African-Americans?

This paper estimates whether marriage can improve health outcomes for African-Americans through changes in risky health behaviors like smoking, drinking, and drug use. Using data from the National Longitudinal Study on Adolescent Health and propensity score matching methodology to account for the potential selection bias, the results show that marriage does lead to a reduction in risky health behaviors, specifically drinking and drug use. This question has important policy implications because if marriage has the same benefits for African-Americans as it does for the general population, social welfare programs can be re-evaluated to incorporate marriage promotion, and further support can be given to programs that decrease adverse health behaviors.

The impact of hepatitis C on labor force participation, absenteeism, presenteeism and non-work activities

Objective:Between 2.7 and 3.9 million people are currently infected with the hepatitis C virus (HCV) in the United States. Although many studies have investigated the impact of HCV on direct healthcare costs, few studies have estimated the indirect costs associated with the virus using a nationally-representative dataset.Methods:Using data from the 2009 United States (US) National Health and Wellness Survey, patients who reported a hepatitis C diagnosis (n = 695) were compared to controls on labor force participation, productivity loss, and activity impairment after adjusting for demographics, health risk behaviors, and comorbidities. All analyses applied sampling weights to project to the population.Results:Patients with HCV were significantly less likely to be in the labor force than controls and reported significantly higher levels of absenteeism (4.88 vs. 3.03%), presenteeism (16.69 vs. 13.50%), overall work impairment (19.40 vs.15.35%), and activity impairment (25.01 vs. 21.78%). A propensity score matching methodology replicated many of these findings.Conclusions:While much of the work on HCV has focused on direct costs, our results suggest indirect costs should not be ignored when quantifying the societal burden of HCV. To our knowledge, this is the first study which has utilized a large, nationally-representative data source for identifying the impact of HCV on labor force participation and work and activity impairment using both a propensity-score matching and a regression modeling framework.Limitations:All data were patient-reported (including HCV diagnosis and work productivity), which could have introduced some subjective biases.

Humanistic and economic impacts of hepatitis C infection in the United States

Objective:Prior research examining the effect of hepatitis C virus (HCV) on health-related quality of life (HRQoL) and healthcare costs is flawed because non-patient controls were not adequately comparable to HCV patients. The current study uses a propensity score matching methodology to address the following research question: is the presence of diagnosed hepatitis C (HCV) associated with poorer health-related quality of life (HRQoL) and greater healthcare resource use?Methods:Using data from the 2009 US National Health and Wellness Survey, patients who reported a HCV diagnosis (n = 695) were compared to propensity-matched controls (n = 695) on measures of HRQoL and healthcare resource use. All analyses applied sampling weights to project to the US population.Results:HCV patients reported significantly lower levels of HRQoL relative to the matched-control group, including the physical component score (39.6 vs. 42.7, p < 0.0001) and health utilities (0.63 vs. 0.66, p < 0.0001). The number of emergency room visits (0.59 vs. 0.44, p < 0.05) and physician visits (7.7 vs. 5.9, p < 0.05) in the past 6 months were significantly higher for the HCV group relative to matched controls.Conclusion:The results of this study suggest that HCV represents a substantial burden on patients by having a significant and clinically-relevant impact on key dimensions of HRQoL as well as on utilization of healthcare resources, the latter of which would result in increased direct medical costs.Limitations:Due to limitations of the internet survey approach (e.g., inability to confirm HCV diagnosis), future research is needed to confirm these findings.

To Cut or Not to Cut a Dividend

Motivated by the argument that managers will cut their dividend only when there are visible signs of poor performance, I revisit the issue of why firms cut their regular cash dividend. I use a propensity score matching methodology to differentiate firms according to their likelihood of cutting a dividend where the likelihood is a function of observable firm characteristics. I have three main findings: First, I find that the market reaction to dividend cut announcements is proportional to the element of surprise. Specifically, for a given magnitude of the dividend cut, I find that the three-day cumulative abnormal return around the dividend cut announcement is more negative for firms with less visible signs of poor performance compared to those that have experienced a more prolonged period of poor performance. Second, while on average firms cut their dividend as a last resort response to poor performance as suggested by prior studies, a significant number of firms cut their dividend pro-actively even without such visible signs of poor performance. The preservation of a low leverage ratio appears to be of first-order importance to these pro-active firms. Third, I find that by and large, firms use their poor performance to justify a dividend cut. Moreover, the absence of concurrent poor performance seems to preclude the option of cutting the dividend. Instead, firms may resort to cut back on capital expenditures.

Evaluation of credit guarantee policy using propensity score matching

In this article, we evaluate the effect of the credit guarantee policy by comparing a large sample of guaranteed firms and matched non-guaranteed firms from 2000 to 2003. The sample firms are compared with respect to growth rates of different performance indicators including: productivity, sales, employment, investment, R&D, wage level, and the survival of firms in the post crisis period. In order to avoid the selectivity problem, propensity score matching methodologies are adopted. Results suggest that credit guarantees influenced significantly firms’ ability to maintain their size, and increase their survival rate, but not to increase their R&D and investment and hence, their growth in productivity. Moreover, due to the adverse selection problem, firms with lower productivity were receiving guarantees.

Can system integration improve mental health outcomes for children and youth?

Objective This article compares mental health outcomes for children receiving services in two federally funded system-of-care communities to those of children in similar communities. Methods Children's clinical and functional outcomes over three waves of data collection for 573 children and youth are analyzed using a propensity score matching methodology. Results Children at one of the two system-of-care sites showed substantially greater improvement than did their matched counterparts. For the other pair, no benefits of the system of care were apparent. Conclusions The differences in the effectiveness of the system of care between the two pairs of sites may reflect differences in system implementation, especially as affecting service use.

A Matched-Cohort Study of Selected Clinical and Utilization Outcomes for an Asthma Care Support Program

Estimating the economic and clinical impact of asthma disease management programs traditionally has relied on non-experimental designs and employed matching or stratification methods with limited success. Selecting similar comparison subjects is problematic since subjects must be compared across numerous pretreatment factors. In cases where treatment and comparison subjects differ greatly on observed characteristics, conclusions may be particularly sensitive to an incorrectly specified model used for matching. A propensity score method constructs matched samples of treated-control pairs, addresses program selection bias, and reduces bias in estimates of treatment effects. To investigate the program effects of an asthma care support program delivered to high-risk asthmatics (persons with a previous inpatient admission, emergency department [ED] visit, or observation visit), we conducted a matched-cohort study on 196 participants. Using administrative claims data and selected clinical indicators, we analyzed hospitalization, ED, and physician office visit rates to estimate effects of program enrollment. Total hospitalizations, asthma-related hospitalizations, bed days, and ED visits for participants were lower and statistically different from that of the matched-cohort group during the program period, suggesting the beneficial effects of monitoring, education, and counseling activities for participants. Where controlled randomized clinical trials cannot be performed because of ethical, cost, or feasibility issues, the use of propensity scores provides an alternative for estimating treatment effects using observational data. This study employs a propensity score-matching methodology to select a subset of comparison units most comparable to treatment units, and documents the beneficial outcomes of participation in an asthma care support program.

A Matched-Cohort Study of Health Services Utilization Outcomes for a Heart Failure Disease Management Program

Chronic disease is the leading cause of illness, disability, and death in the United States, affecting nearly 100 million Americans. Heart failure alone affects nearly 4.9 million Americans, with another 550,000 newly diagnosed cases each year. The aim of this study was to investigate the program effects of a heart failure care support program. A two-group cohort study matching on propensity scores was used to investigate 277 heart failure care support program participants and corresponding matched non-participants. Measures used were rates of hospitalizations, emergency department visits, physician office visits, and heart failure-related prescription drug use and procedures. Relative to the matched control group, program participants experienced 26.3% (p = 0.023) fewer inpatient admissions, 37.9% (p = 0.018) inpatient bed days, 33.3% (p = 0.059) more beta blocker use, 76.7% (p = 0.048) more alpha blocker use, 22.2% (p = 0.006) more lipid panels, 13.4% (p = 0.019) more electrocardiographies, 50.0% (p = 0.008) fewer cardiac catheterizations, and 94.6% (p = 0.014) more pneumonia vaccinations. The current study employs a propensity score matching methodology to select a subset of comparison patients most comparable to treatment patients, and documents the beneficial health services outcomes of participation in a heart failure care support program.