Difference-in-differences Estimate Research Articles

Universal healthcare coverage and health service delivery before and during the COVID-19 pandemic: A difference-in-difference study of childhood immunization coverage from 195 countries.

Several studies have indicated that universal health coverage (UHC) improves health service utilization and outcomes in countries. These studies, however, have primarily assessed UHC's peacetime impact, limiting our understanding of UHC's potential protective effects during public health crises such as the Coronavirus Disease 2019 (COVID-19) pandemic. We empirically explored whether countries' progress toward UHC is associated with differential COVID-19 impacts on childhood immunization coverage. Using a quasi-experimental difference-in-difference (DiD) methodology, we quantified the relationship between UHC and childhood immunization coverage before and during the COVID-19 pandemic. The analysis considered 195 World Health Organization (WHO) member states and their ability to provision 12 out of 14 childhood vaccines between 2010 and 2020 as an outcome. We used the 2019 UHC Service Coverage Index (UHC SCI) to divide countries into a "high UHC index" group (UHC SCI ≥80) and the rest. All analyses included potential confounders including the calendar year, countries' income group per the World Bank classification, countries' geographical region as defined by WHO, and countries' preparedness for an epidemic/pandemic as represented by the Global Health Security Index 2019. For robustness, we replicated the analysis using a lower cutoff value of 50 for the UHC index. A total of 20,230 country-year observations were included in the study. The DiD estimators indicated that countries with a high UHC index (UHC SCI ≥80, n = 35) had a 2.70% smaller reduction in childhood immunization coverage during the pandemic year of 2020 as compared to the countries with UHC index less than 80 (DiD coefficient 2.70; 95% CI: 0.75, 4.65; p-value = 0.007). This relationship, however, became statistically nonsignificant at the lower cutoff value of UHC SCI <50 (n = 60). The study's primary limitation was scarce data availability, which restricted our ability to account for confounders and to test our hypothesis for other relevant outcomes. We observed that countries with greater progress toward UHC were associated with significantly smaller declines in childhood immunization coverage during the pandemic. This identified association may potentially provide support for the importance of UHC in building health system resilience. Our findings strongly suggest that policymakers should continue to advocate for achieving UHC in coming years.

Effect of State-Led Delivery System and Payment Reforms on Population-Level Detection and Management of Diabetes.

The Centers for Medicare and Medicaid Services State Innovation Models (SIM) initiative has invested more than $1 billion to test state-led delivery system and payment reforms that can affect diabetes care management. We examined whether SIM implementation between 2013 and 2017 was associated with diagnosed diabetes prevalence or with hospitalization or 30-day readmission rate among diagnosed adults. The quasiexperimental design compared study outcomes before and after the SIM initiative in 12 SIM states versus five comparison states using difference-in-differences (DiD) regression models of 21,055,714 hospitalizations for adults age ≥18 years diagnosed with diabetes in 889 counties from 2010 to 2017 across the 17 states. For readmission analyses, comparative interrupted time series (CITS) models included 11,812,993 hospitalizations from a subset of nine states. Diagnosed diabetes prevalence changes were not significantly different between SIM states and comparison states. Hospitalization rates were inconsistent across models, with DiD estimates ranging from -5.34 to -0.37 and from -13.16 to 0.92, respectively. CITS results indicate that SIM states had greater increases in odds of 30-day readmission during SIM implementation compared with comparison states (round 1: adjusted odds ratio [AOR] 1.07; 95% CI 1.04, 1.11; P < 0.001; round 2: AOR 1.06; 95% CI 1.03, 1.10; P = 0.001). The SIM initiative was not sufficiently focused to have a population-level effect on diabetes detection or management. SIM states had greater increases in 30-day readmission for adults with diabetes than comparison states, highlighting potential unintended effects of engaging in the multipayer alignment efforts required of state-led delivery system and payment reforms.

Association of topiramate prescribed for any indication with reduced alcohol consumption in electronic health record data.

Topiramate is a medication that is widely prescribed to treat a variety of conditions, including alcohol use disorder (AUD). We used electronic health record (EHR) data to measure topiramate's effects on drinking in individuals differentiated by a history of AUD. Parallel-groups comparison of patients prescribed topiramate and a propensity score-matched comparison group. A large US integrated health-care system. Patients with Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) scores prior to and after a minimum of 180 days of topiramate prescription for any indication and a propensity score-matched group. The sample included 5918 patients with an electronic health record diagnosis of alcohol use disorder at any time (AUD-hx-pos) (1738 topiramate-exposed and 4180 controls) and 23 614 patients with no EHR diagnosis of AUD (AUD-hx-neg) (6324 topiramate-exposed and 17 290 controls). Regression analyses compared difference-in-difference (DiD) estimates, separately by AUD history. DiD estimates represent exposure-group (i.e. topiramate versus control) differences on the pre-post difference in AUDIT-C score. Effects of baseline AUDIT-C score and daily topiramate dosage were also tested. AUD-hx-neg patients who received topiramate had a greater reduction in AUDIT-C score (-0.11) than matched controls (-0.04). This yielded a DiD score of -0.07 [95% confidence interval (CI) = -0.11,-0.03; P = 0.002], with the greatest effect among AUD-hx-neg patients with a baseline AUDIT-C score of 4+ (DiD = -0.35, 95% CI = -0.49, -0.21; P < 0.0001) and those prescribed > 150 mg/day of the medication (DiD = -0.15, 95%CI = -0.23, -0.07; P < 0.001). Among individuals with no history of alcohol use disorder, topiramate appears to be associated with reduced drinking. This small effect is most evident among patients with higher baseline drinking levels and at a higher average daily topiramate dosage.

처치집단에 대한 평균 처치 효과의 준모수적 추정

In this study, Abadie(2005)’s semiparametric difference-in-difference(DID) and propensity score matching DID methods are implemented to estimate the average treatment effect on the treated(ATET) of the Anti-Graft Act on the expenditure on congratulations and condolences(ECC). Both approaches are semiparametric since they do not require a specific functional form specification of the outcome variable. By following Abadie(2005), the ATET can be estimated by using observed outcomes at before and after policy intervention, treatment indicator and propensity score of all observations. On the other hand, the propensity score matching DID is a very intuitive method to estimate ATET since it can find a counterfactual control for each treated unit. Abadie’s semiparametric DID estimate is -0.06 while the propensity score matching estimate is -0.12. However, the statistical significance is found only in the latter estimation result. It implies that the treatment group are expected to reduce the expenditure on congratulations and condolences by 12.8 percent less than the control group if the control group would be exposed to the treatment.

Do refugees cause crime?

• There is not any statistically significant impact of the Syrian refugees on crime rates in Turkey in the short-run (1-year after the treatment). • Staggered difference-in-differences analysis shows that the provinces where refugees make up over 1 percent of the total population do not demonstrate any statistically significant impact on their crime rates in the long run, either. • There is a negative impact of treatment intensity on crime rates per capita when the impact of refugee population share is analyzed using an instrumental variables strategy. The same analysis for the crime rates per native resident produces null effects. • Overall, the empirical analyses provide causal evidence for a rather lower propensity of crime commitment among the Syrian refugees in Turkey compared to the country’s native population. The null effects of refugees on crime rates per native resident, on the other hand, can be interpreted as a non-significant spillover effect of refugees on native criminality. • Higher expected costs of crime commitment for refugees such as deportation and negligible adverse impacts of them, on average, on the natives’ labor market outcomes, among other mechanisms, might have played an important role in these findings. The impact of immigration on crime continues to stir heated debates in public policy circles around the world. Surveys indicate that host societies favor controversial measures because they are concerned about what they perceive to be an impingement exacted on their security with each new wave of migration. Seeking whether there is any truth to such perceptions, this paper analyzes the refugees’ impact on crime rates, using the case of Turkey which has started to host the world’s largest refugee population within any national borders due to the Syrian civil war. In doing so, the paper employs instrumental variables, difference-in-differences (DiD), and staggered DiD methods to explain if the conflict-fleeing Syrians have pushed Turkey’s crime rates higher in the short and the long run. It also controls for a multitude of time-varying provincial characteristics and presents a battery of robustness checks against various identification threats. As a result, DiD estimates show that refugees do not have any causal effect on the crime rates in Turkey. More strikingly, its IV estimates provide evidence for a rather negative effect on the crime rates per capita whilst finding a null effect on the crime rates per native resident in particular.

Effects of e-cigarette use on mental health among youths: quasi-experimental evidence from Canada.

Existing research on mental health comorbidities of youth e-cigarette use is subject to confounding bias and reverse causality. This study aimed to measure the effects of e-cigarette use on youth mental health, using e-cigarette minimum legal age (MLA) law in Canada as a natural experiment. We used difference-in-differences (DD), difference-in-differences-in-differences (DDD) and two-sample instrumental variables (TSIV) methods. Data were from nationally representative Canadian Community Health Surveys 2008-2019 and Canadian Student Tobacco Alcohol and Drugs Surveys 2008-2019. The study sample comprised of respondents aged 15 to 18 (in DD analysis; n = 33 858) and aged 15 to 24 (in DDD analysis; n = 78 689). Primary outcomes were self-reported mood disorders and anxiety disorders. Secondary outcomes were cannabis use, illicit drug use, cigarette use and strength of peer relationships at schools. After the e-cigarette MLA laws, risks of mood disorders declined by 1.9 percentage points (95% CI, 0.0-3.8; P =0.05) in the DD analysis and by 2.6 percentage points (95% CI, 0.2-5.0; P =0.03) in the DDD analysis. For anxiety disorders, while the DD estimate was negative but imprecisely estimated, the MLA law reduced risks of anxiety disorder by 3.6 percentage points (95% CI, 0.9-6.2; P = 0.01) in the DDD analysis. Youths in provinces with MLA laws were also less likely to report cannabis use and illicit drug use and more likely to feel being part of schools. TSIV analysis indicates that youth e-cigarette use increased the likelihood of mood and anxiety disorders by 44% and 37%, respectively. In Canada, the e-cigarette minimum legal age law appears to have reduced risks of mood and anxiety disorders, lowered substance use and improved peer relationships at schools. Combined with previous evidence of lower e-cigarette use following the minimum legal age law, our findings indicate that youth e-cigarette use increases risks of mood and anxiety disorders.

Effect of health facility linkage with community using postnatal card on postnatal home visit coverage and newborn care practices in rural Ethiopia: A controlled quasi-experimental study design.

BackgroundPostnatal home visit has the potential to improve maternal and newborn health, but it remains as a missed opportunity in many low-and middle-income countries. This study examines the effect of health extension worker administered postnatal card combined with health facility strengthening intervention on postnatal home visit coverage, newborn care practices, and knowledge of newborn danger signs in rural Ethiopia.MethodsWe employed quasi-experimental design using controlled before-and-after study in intervention and comparison districts of rural Tigray, northern Ethiopia. Training of health extension workers (HEWs) on postnatal home visit (PNHV), training of healthcare providers on maternal and newborn care, and capacity building of healthcare authorities on leadership, management and governance together with health system strengthening were the implemented interventions. Baseline (n = 705) and end line (n = 980) data were collected from mothers who delivered a year before the commencement of the actual data collection in the respective surveys. We used difference-in-differences (DiD) analysis to assess the effect of the intervention on PNHV coverage, essential newborn care practices and maternal knowledge of newborn danger signs.ResultsA total of 1685 (100%) mothers participated in this study. In all districts, more than 1/3rd of the mothers 633(37.57%) were in the age of 30–39 years. The difference-in-differences estimator showed an average of 23.5% increase in coverage of PNHVs within three days (DiD, p<0.001) and the provision of most postnatal contents significantly increased in the intervention district in the end line survey. The knowledge of at least three danger signs increased by 13.6% (p = 0.012).The DiD estimator showed an average of 27.6% increase to check the mothers for heavy bleeding (DiD, p = 0.011). This study also revealed that the checking of maternal blood pressure increased from 5.8% to 11.8% in the comparison districts and from 9.4% to 93.3% in the intervention district. The difference-in-differences estimator result showed a 9% difference in clean cord care practices among the participants (p = 0.025), 12.2% in skin to skin care (p = 0.022), and borderline significant increase in early initiation of breastfeeding (10.5%, p = 0.051).ConclusionWe conclude that the intervention package was effective in improving the coverage of PNHV, increase in knowledge of newborn danger sign and essential newborn care practices. Hence, further strengthening the linkages between health facilities and community is imperative to improve the coverage of essential lifesaving maternal and newborn care services by HEWs at home.

RETRACTED ARTICLE: The effect of firm size, industry type and ownership structure on the relationship between firms' sustainable innovation capability and stock liquidity

Does the company attach importance to research and development (R&D) investment in its operations? Is stock liquidity detrimental to corporate innovation and thus damages the company’s sustainable development capabilities? We estimate the relationship between between stock liquidity and firms’ sustainable innovation capability on China’s stock market by OLS method and difference in difference (DID) method. The traditional conclusion is: the higher the stock liquidity, the weaker the enterprise's sustainable innovation level, especially in state-owned enterprises. The DID estimation using the share-trading reform and the policy of large and small-sized non-tradable share shows that: stock liquidity will affect the sustainable innovation level of the enterprise positively. The reasons for this mechanism are the supervision mechanism in the operation of the enterprise, the effect of the balance of the ownership structure and the improvement of corporate governance. The conclusions are that the improvement of ownership concentration promotes this positive relationship, and the behavior of institutional investors does not have a significant impact. These findings also provide new insights into the relationship between corporate management and shareholder investment behavior on the level of innovation.

Impact of Statewide Mandatory Medicaid Managed Care (SMMC) Programs on Hospital Obstetric Outcomes.

The state of Florida implemented mandatory managed care for Medicaid enrollees via the Statewide Medicaid Managed Care (SMMC) program in April of 2014. The objective of this study was to examine the impact of the implementation of the SMMC program on the access to care and quality of maternal care for Medicaid enrollees, as measured by several hospital obstetric outcomes. The primary data source for this retrospective observational study was the Hospital Cost and Utilization Project (HCUP) all-payer State ED (SED) visit and State Inpatient Databases (SIDs) from 2010 to 2017. The primary health outcomes for obstetric care were primary cesarean, preterm birth, postpartum preventable ED visits, postpartum preventable readmissions, and vaginal delivery after cesarean (VBAC) rates. Using difference-in-differences (DID) estimation, selected health outcomes were examined for Florida residents with Medicaid beneficiaries (treatment) and the commercially insured population (comparison), before and after the implementation of SMMC. Improvement in disparities for racial/ethnic minority Medicaid enrollees was estimated relative to whites, compared to the relative change among commercially insured patients. From the DID estimation, the findings showed that SMMC is statistically significantly associated with a higher reduction in primary cesarean rates, preterm births, preventable postpartum ED visits, and readmissions among Medicaid beneficiaries relative to their commercially insured counterparts. However, this study did not find any significant reduction in racial/ethnic disparities in obstetric outcomes. In general, this study highlights the impact of SMMC implementation on obstetric outcomes in Florida and provides important insights and potential scope for improvement in obstetric care quality and associated racial/ethnic disparities.

Mental and Physical Health Effect of Rural-Urban Migration in South Africa: A Quasi-Experimental Impact Evaluation Study

Using the National Income Dynamics Study (NIDS) longitudinal dataset, this study undertakes a difference-in-differences (DiD) evaluation of the impact of rural-urban migration on mental and physical health in South Africa. The contribution of the study is in considering sample selection bias as well as the causal direction of the relationship through the use of propensity score matching techniques and restricted sample DiD estimation. This study finds that the rural-urban migrants, within the South African NIDS sample, experience a decline in reported physical and mental health outcomes. The study identifies social isolation and difficult living conditions as some of the factors behind the adverse health outcomes. The findings underscore the fact that while favourable economic outcomes will likely occur as a result of migration efforts (such as employment opportunities and increased income), it comes at a cost of both physical and mental health.

The consequence of financial incentives for not prescribing antibiotics: a Japan's nationwide quasi-experiment.

For addressing antibiotic overuse, Japan designed a health care policy in which eligible medical facilities could claim a financial reward when antibiotics were not prescribed for early-stage respiratory and gastrointestinal infections. The policy was introduced in a pilot manner in paediatric clinics in April 2018. We conducted a quasi-experimental, propensity score-matched, difference-in-differences (DID) design to determine whether the nationwide financial incentives for appropriate non-prescribing of antibiotics as antimicrobial stewardship [800 JPY (≈7.3 US D) per case] were associated with changes in prescription patterns, including antibiotics, and health care use in routine paediatric health care settings at a national level. Data consisted of 9 253 261 cases of infectious diseases in 553 138 patients treated at 10 180 eligible or ineligible facilities. A total of 2959 eligible facilities claimed 316 770 cases for financial incentives and earned 253 million JPY (≈2.29 million USD). Compared with ineligible facilities, the introduction of financial incentives in the eligible facilities was associated with an excess reduction in antibiotic prescriptions [DID estimate, -228.6 days of therapy (DOTs) per 1000 cases (95% CI, -272.4 to -184.9), which corresponded to a relative reduction of 17.8% (95% CI, 14.8 to 20.7)]. The introduction was also associated with excess reductions in drugs for respiratory symptoms [DID estimates, -256.9 DOTs per 1000 cases (95% CI, -379.3 to -134.5)] and antihistamines [DID estimate, -198.5 DOTs per 1000 cases (95% CI, -282.1 to -114.9)]. There was no excess in out-of-hour visits [DID estimate, -4.43 events per 1000 cases (95% CI, -12.8 to 3.97)] or hospitalizations [DID estimate, -0.08 events per 1000 cases (95% CI, -0.48 to 0.31)]. Our findings suggest that financial incentives to medical facilities for not prescribing antibiotics were associated with reductions in prescriptions for antibiotics without adverse health care consequences. Japan's new health policy provided us with policy options for immediately reducing inappropriate antibiotic prescriptions by relatively small financial incentives.

Using Multiple Pretreatment Periods to Improve Difference-in-Differences and Staggered Adoption Designs

AbstractWhile a difference-in-differences (DID) design was originally developed with one pre- and one posttreatment period, data from additional pretreatment periods are often available. How can researchers improve the DID design with such multiple pretreatment periods under what conditions? We first use potential outcomes to clarify three benefits of multiple pretreatment periods: (1) assessing the parallel trends assumption, (2) improving estimation accuracy, and (3) allowing for a more flexible parallel trends assumption. We then propose a new estimator, double DID, which combines all the benefits through the generalized method of moments and contains the two-way fixed effects regression as a special case. We show that the double DID requires a weaker assumption about outcome trends and is more efficient than existing DID estimators. We also generalize the double DID to the staggered adoption design where different units can receive the treatment in different time periods. We illustrate the proposed method with two empirical applications, covering both the basic DID and staggered adoption designs. We offer an open-source R package that implements the proposed methodologies.

COVID-19 pandemic-related change in racial and ethnic disparities in exclusive breastmilk feeding during the delivery hospitalization: a differences-in-differences analysis

ObjectiveExclusive breastmilk feeding during the delivery hospitalization, a Joint Commission indicator of perinatal care quality, is associated with longer-term breastfeeding success. Marked racial and ethnic disparities in breastfeeding exclusivity and duration existed prior to COVID-19. The pandemic, accompanied by uncertainty regarding intrapartum and postpartum safety practices, may have influenced disparities in infant feeding practices. Our objective was to examine whether the first wave of the COVID-19 pandemic in New York City was associated with a change in racial and ethnic disparities in exclusive breastmilk feeding during the delivery stay.MethodsWe conducted a cross-sectional study of electronic medical records from 14,964 births in two New York City hospitals. We conducted a difference-in-differences (DID) analysis to compare Black-white, Latina-white, and Asian-white disparities in exclusive breastmilk feeding in a pandemic cohort (April 1-July 31, 2020, n=3122 deliveries) to disparities in a pre-pandemic cohort (January 1, 2019-February 28, 2020, n=11,842). We defined exclusive breastmilk feeding as receipt of only breastmilk during delivery hospitalization, regardless of route of administration. We ascertained severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection status from reverse transcription-polymerase chain reaction tests from nasopharyngeal swab at admission. For each DID model (e.g. Black-white disparity), we used covariate-adjusted log binomial regression models to estimate racial and ethnic risk differences, pandemic versus pre-pandemic cohort risk differences, and an interaction term representing the DID estimator.ResultsExclusive breastmilk feeding increased from pre-pandemic to pandemic among white (40.8% to 46.6%, p<0.001) and Asian (27.9% to 35.8%, p=0.004) women, but not Black (22.6% to 25.3%, p=0.275) or Latina (20.1% to 21.4%, p=0.515) women overall. There was an increase in the Latina-white exclusive breastmilk feeding disparity associated with the pandemic (DID estimator=6.3 fewer cases per 100 births (95% CI=-10.8, -1.9)). We found decreased breastmilk feeding specifically among SARS-CoV-2 positive Latina women (20.1% pre-pandemic vs. 9.1% pandemic p=0.013), and no change in Black-white or Asian-white disparities.ConclusionsWe observed a pandemic-related increase in the Latina-white disparity in exclusive breastmilk feeding, urging hospital policies and programs to increase equity in breastmilk feeding and perinatal care quality during and beyond this health emergency.

Association between indoor residual spraying and pregnancy outcomes: a quasi-experimental study from Uganda.

Malaria is a risk factor for adverse pregnancy outcomes. Indoor residual spraying with insecticide (IRS) reduces malaria infections, yet the effects of IRS on pregnancy outcomes are not well established. We evaluated the impact of a large-scale IRS campaign on pregnancy outcomes in Eastern Uganda. Birth records (n = 59 992) were obtained from routine surveillance data at 25 health facilities from five districts that were part of the IRS campaign and six neighbouring control districts ∼27 months before and ∼24 months after the start of the campaign (January 2013-May 2017). Campaign effects on low birthweight (LBW) and stillbirth incidence were estimated using the matrix completion method (MC-NNM), a machine-learning approach to estimating potential outcomes, and compared with the difference-in-differences (DiD) estimator. Subgroup analyses were conducted by HIV and gravidity. MC-NNM estimates indicated that the campaign was associated with a 33% reduction in LBW incidence: incidence rate ratio (IRR) = 0.67 [95% confidence interval (CI): 0.49-0.93)]. DiD estimates were similar to MC-NNM [IRR = 0.69 (0.47-1.01)], despite a parallel trends violation during the pre-IRS period. The campaign was not associated with substantial reductions in stillbirth incidence [IRRMC-NNM = 0.94 (0.50-1.77)]. HIV status modified the effects of the IRS campaign on LBW [βIRSxHIV = 0.42 (0.05-0.78)], whereby HIV-negative women appeared to benefit from the campaign [IRR = 0.70 (0.61-0.81)], but not HIV-positive women [IRR = 1.12 (0.59-2.12)]. Our results support the effectiveness of the campaign in Eastern Uganda based on its benefit to LBW prevention, though HIV-positive women may require additional interventions. The IRS campaign was not associated with a substantively lower stillbirth incidence, warranting further research.

Impact of the introduction of a low-cost uterine balloon tamponade (ESM-UBT) device for managing severe postpartum hemorrhage in India: A comparative before-and-after study.

To evaluate the impact of introducing a uterine balloon tamponade (ESM-UBT) device for managing severe postpartum hemorrhage (PPH), mainly due to uterine atony, in health facilities in India on the rates of PPH-related maternal death and invasive procedures for PPH control. We used a quasi-experimental, difference-in-difference (DID) design to compare changes in the rates of a composite outcome (PPH-related maternal death and/or artery ligation, uterine compression sutures, or hysterectomy) among women delivering in nine intervention facilities compared with those delivering in two control facilities, before and after the introduction of ESM-UBT. The study sample included 214 123 deliveries (n=78 509 before ESM-UBT introduction; n=47 211 during ESM-UBT introduction; and n=88 403 after ESM-UBT introduction). After introduction of ESM-UBT, there was a significant decline in the rate of the primary composite outcome in intervention facilities (21.0-11.4 per 10000 deliveries; difference -9.6, 95% confidence interval -14.0 to -5.4). Change in the rate of the primary composite outcome was not significant in control facilities (11.7-17.2 per 10000 deliveries; difference 5.4, 95% confidence interval -3.9 to 14.9). DID analyses showed there was a significant reduction in the rate of the primary composite outcome in intervention facilities relative to control facilities (adjusted DID estimate -15.0 per 10000 points, 95% confidence interval -23.3 to -6.8; P=0.005). Introduction of the ESM-UBT in health facilities in India was associated with a significant reduction in PPH-related maternal death and/or invasive procedures for PPH control.

Excess healthcare spending associated with fractures among adults with cerebral palsy

BackgroundFractures represent a triple threat to adults with cerebral palsy (CP): common, accumulate early in adulthood, and are consequential to health. An economic evaluation of fractures in CP is needed to highlight priorities for allocating resources to clinical and public health programs aimed at preventing fractures and their disease sequela. ObjectiveTo identify short-term healthcare costs associated with fractures among adults with CP. MethodsA retrospective cohort study was performed using Optum's de-identified Clinformatics® Data Mart Database from 01/01/2011-12/31/2017. The primary cohort included adults ≥ 18 years old with CP with an incident fracture (CP+Fx), and cost estimates were compared with: CP without fractures (CPw/oFx) and without CP+Fx (w/oCP+Fx). A difference-in-difference (DiD) analysis compared the change in pharmacy and medical costs between cohorts from the one-year baseline period through the one-year post-index period in three-month quarters. ResultsCP+Fx (n = 855) had higher mean costs in the baseline and follow-up periods compared with CPw/oFx (n = 5667) and w/oCP+Fx (n = 588,042). The first post-index quarter DiD estimate suggests that CP+Fx accumulated an excess $6462 (95%CI = $3810-$9021) compared with w/oCP+Fx and $17,197 (95%CI = $14,418-$19,833) compared with CPw/oFx. The CP+Fx cohort had higher DiD estimates in the other follow-up quarters, but they were not statistically significant compared with CPw/oFx. When stratified by fracture site, vertebral column fractures for CP+Fx vs. w/oCP+Fx accumulated an excess $25,226 (95%CI = $12,639-$37,417). ConclusionsFractures, especially of the vertebral column, were associated with high healthcare costs among adults with CP. Studies are needed to identify cost-effective opportunities to utilize available resources to prevent fractures and their costly sequela for CP.

Statistical Power for Estimating Treatment Effects Using Difference-in-Differences and Comparative Interrupted Time Series Estimators With Variation in Treatment Timing

This article develops new closed-form variance expressions for power analyses for commonly used difference-in-differences (DID) and comparative interrupted time series (CITS) panel data estimators. The main contribution is to incorporate variation in treatment timing into the analysis. The power formulas also account for other key design features that arise in practice: autocorrelated errors, unequal measurement intervals, and clustering due to the unit of treatment assignment. We consider power formulas for both cross-sectional and longitudinal models and allow for covariates. An illustrative power analysis provides guidance on appropriate sample sizes. The key finding is that accounting for treatment timing increases required sample sizes. Further, DID estimators have considerably more power than standard CITS and ITS estimators. An available Shiny R dashboard performs the sample size calculations for the considered estimators.

The effect of Medicaid expansion on state-level utilization of buprenorphine for opioid use disorder in the United States

BackgroundResearch on the impact of Medicaid expansion on buprenorphine utilization has largely focused on the Medicaid program. Less is known about its associations with total buprenorphine utilization and non-Medicaid payers. MethodsMonthly prescription data (June 2013-May 2018) for proprietary and generic sublingual as well as buccal buprenorphine products were purchased from IQVIA®. Population-adjusted state-level utilization measures were constructed for Medicaid, commercial insurance, Medicare, cash, and total utilization. A difference-in-differences (DID) approach with population weights estimated the association between Medicaid expansion and buprenorphine utilization, while controlling for treatment capacity. ResultsMonthly total buprenorphine prescriptions increased by 68% overall and increased 283% for Medicaid, 30% for commercial insurance, and 143% for Medicare. Cash prescriptions decreased by 10%. The DID estimate for Medicaid expansion was not statistically significant for total utilization (−19.780, 95% CI = −45.118, 5.558, p = .123). For Medicaid buprenorphine utilization, there was a significant increase of 27.120 prescriptions per 100,000 total state residents (95% CI = 9.458, 44.782, p = .003) in expansion states versus non-expansion states post-Medicaid expansion. Medicaid expansion had a negative effect on commercial insurance (DID estimate = −37.745, 95% CI = −62.946, −12.544, p = .004), cash utilization (DID estimate = −6.675, 95% CI = −12.627, −0.723, p = .029), and Medicare utilization (DID estimate = −1.855, 95% CI = −3.697, −0.013, p = .048). DiscussionThe associations between Medicaid expansion and buprenorphine utilization varied across different types of payers, such that the overall impact of Medicaid expansion on buprenorphine utilization was not significant.

Does industrial transfer policy mitigate carbon emissions? Evidence from a quasi-natural experiment in China

In this paper, we identify the causal effects of the industrial transfer policy (ITP) on carbon emissions. Specifically, we treat the demonstration zones of undertaking industrial transfer in China as a quasi-natural experiment and evaluation its carbon mitigation effects using the difference-in-differences (DID) and matching DID strategies. Our findings suggest that the ITP exerts a significant negative impact on carbon emissions. In particular, both the DID and matching DID estimates indicate that the ITP leads to mitigate carbon emissions by approximately 4.9 and 4.7 million tons, respectively. We also investigate the heterogeneous carbon mitigation effects of the ITP. Moreover, various checks and falsification tests are also presented to confirm the causal effects, including the placebo test, concurrent events test, alternative measures of the ITP and carbon emissions, alternative estimation method and matching technique. The results indicate that our key conclusion, the carbon mitigation effect of the ITP is robust. These results indicate that policymakers should seize the carbon mitigation dividend of the ITP to achieve the goal of carbon neutrality. Policymakers should also reduce the regional development differences, improve the level of opening to the outside world, strengthen the construction of green demonstration zones for industrial transfer to mitigate carbon emissions.

Effects of ordinances prohibiting smoking in private homes with children following smoke-free household rules in Tokyo

Objectives Exposure to secondhand smoke is harmful to children's health. Therefore, the Tokyo metropolitan area implemented an ordinance on April 1st, 2018 that prohibits smoking in private homes when children are present. To date, the effect of this ordinance has not been studied. In this study, we evaluated the change in the percentage of residents in the Tokyo metropolitan area who have smoke-free household rules using difference-in-difference (DID) analysis.Methods A one year, follow-up, longitudinal internet survey of the general Japanese population was conducted from 2018 to 2019 (Japan Society and New Tobacco Internet Survey, JASTIS). DID analysis was conducted using the percentage of residents who have smoke-free household rules in Tokyo metropolitan area and control groups in 2018 and 2019.Results We utilized three control groups (Control 1: residents in Japan except from Tokyo metropolitan area; Control 2: residents in Japan except from Kanto region; Control 3: residents in prefectures which have ordinance-designated city) for DID analysis. Covariate-adjusted DID estimates for each control group were -1.0 percentage points (Control 1, 95% Confidence Interval (CI)=-5.8, 3.9), -1.0 percentage points (Control 2, 95% CI=-5.9, 4.0), and -1.0 percentage points (Control 3, 95% CI=-5.9, 3.9) indicating that there was no significant difference for all control groups. Moreover, no significant difference was observed when respondents' answers were analyzed and stratified according to sex, age, household income, housing tenure, smoking status, education, or marital status.Conclusions DID analysis revealed no significant change in the percentage of residents of the Tokyo metropolitan area who have smoke-free household rules after the implementation of the ordinance. This study will be useful for local governments when planning and promoting more effective smoke-free ordinances.