Tag: statistics

J Neurosurg Pediatr. 2026 Apr 3:1-9. doi: 10.3171/2025.11.PEDS25497. Online ahead of print.

ABSTRACT

OBJECTIVE: Selective dorsal rhizotomy (SDR) is a surgical procedure to reduce spasticity and improve function in children with cerebral palsy (CP). Randomized trials have shown that SDR is superior to physical therapy alone for reduction of spasticity and improvement in gait, but there is wide variation in surgical technique. The purpose of this study was to describe the scope of patient factors and surgical technique of SDR performed for the management of spasticity in children with CP.

METHODS: This study is a cross-sectional analysis of data included in the Cerebral Palsy Research Network (CPRN) registry from all subjects who underwent SDR at a CPRN member site. Data from consecutive cases were collected at each site and submitted to the CPRN registry. All cases of SDR submitted to the registry were included. Descriptive statistics were used to summarize data. When possible, results were compared across CPRN centers and patients using descriptive and inferential statistics.

RESULTS: A total of 564 patients underwent SDR and had data in the CPRN registry. Most (n = 356, 63%) children were male and White (n = 427, 76%). The Gross Motor Function Classification System (GMFCS) level was I in 63 (14%), II in 108 (23%), III in 134 (29%), IV in 81 (17%), and V in 76 (16%) children. Dystonia was present in 25 (6.2%) children. SDR was performed at the level of the conus medullaris or upper cauda equina in 193 (50%) children. Multilevel laminotomy was performed in 194 (50%) children. Intramuscular monitoring electrodes were placed in 486 (94%) children. The median number of nerve rootlets tested on each side was 27 (IQR 31-34, range 4-139). The median proportion of rootlets cut was 0.63 (IQR 0.52-0.67, range 0.21-1.0). The proportion of rootlets cut was associated with GMFCS level; patients who had a GMFCS level of V had a greater proportion of rootlets cut compared to those with levels of I (mean difference [MD] 0.079, p < 0.01), II (MD 0.129, p < 0.01), and III (MD 0.096, p < 0.01).

CONCLUSIONS: There are many variations in SDR technique for the management of spasticity in CP, including differences in approach to surgical site, number of rootlets tested, and proportion cut. Detailed outcome data are needed to compare variations and determine if an optimal technique is associated with ideal treatment results.

PMID:41931847 | DOI:10.3171/2025.11.PEDS25497

J Neurosurg Spine. 2026 Apr 3:1-10. doi: 10.3171/2025.11.SPINE25662. Online ahead of print.

ABSTRACT

OBJECTIVE: Degenerative cervical myelopathy (DCM) is a progressive condition that results in significant neurological decline and disability. Racial and ethnic disparities in healthcare access and outcomes are well documented, yet their impact on DCM patients remains insufficiently explored. This study aimed to investigate racial and ethnic disparities in self-reported health status and quality of life (QOL), health literacy, and healthcare access among individuals with DCM using data from the All of Us Research Program (AoURP).

METHODS: In this retrospective study, the authors analyzed the data of AoURP participants with a diagnosis of DCM based on ICD-9 and ICD-10 codes. Race and ethnicity were categorized as White/Caucasian (WC), Black/African American (BAA), and non-White Hispanic (NWH). Participants’ demographic characteristics, socioeconomic status (SES), self-reported health status and QOL, health literacy, and healthcare utilization patterns were assessed through survey responses. To assess whether SES mediates the association between race and ethnicity and outcomes, a causal mediation analysis was conducted, operationalizing SES as a composite of standardized income, education, and employment measures. Statistical analyses were conducted using chi-square and independent t-tests to compare categorical and continuous variables, respectively.

RESULTS: Among 3092 DCM patients, 26% identified as BAA, 64% as WC, and 10% as NWH. Significant socioeconomic disparities were observed, with WC participants reporting higher educational attainment, income, and homeownership rates (p < 0.001). Healthcare access varied substantially, with BAA and/or NWH participants reporting lower rates of insurance coverage, specialist consultations, and primary care access compared to WC participants (p ≤ 0.05). Financial and transportation barriers to care access were more frequently reported among minority groups. BAA and NWH participants also had lower health literacy, reporting greater difficulty in understanding medical information and completing medical forms and requiring assistance with health materials (p < 0.001). Furthermore, both BAA and NWH groups reported poorer self-perceived health and QOL and higher pain levels (p < 0.001). Causal mediation analysis demonstrated that SES partially mediated the relationship between race and ethnicity and key outcomes, including health literacy, healthcare access, and self-perceived health, indicating that socioeconomic disadvantage explains much, but not all, of the observed disparities.

CONCLUSIONS: This study highlights substantial racial and ethnic disparities in healthcare access, health literacy, and self-reported health status and QOL among DCM patients, which are partially mediated by socioeconomic factors. Recognizing and addressing these disparities is essential to improving DCM outcomes and ensuring equitable care.

PMID:41931843 | DOI:10.3171/2025.11.SPINE25662

J Neurosurg Spine. 2026 Apr 3:1-10. doi: 10.3171/2025.10.SPINE25539. Online ahead of print.

ABSTRACT

OBJECTIVE: Pedicle subtraction osteotomy (PSO) is a powerful technique for sagittal plane deformity correction. The authors aimed to investigate the differences in radiographic outcomes and rates of distal junctional problems (DJPs) between L3 and L4 PSOs.

METHODS: Patients who underwent L3 or L4 PSO at a quaternary care center between 2005 and 2021 were retrospectively identified. DJPs were defined as either hardware failure or pseudarthrosis distal to the PSO level.

RESULTS: In total, 116 patients were included: 86 (74.1%) underwent L3 PSO and 30 (25.9%) underwent L4 PSO. The mean imaging follow-up was 4.1 (range 1.0-10.9) years. There were no statistically significant differences in age, sex, BMI, operative time, and estimated blood loss. Preoperatively, there were no significant differences in mean sacral Hounsfield units and spinopelvic parameters, with the exception of pelvic incidence (PI; L3: 51.1° ± 11.2° vs L4: 57.9° ± 14.1°, p = 0.012) and the L1 pelvic angle (L3: 23.6° ± 10.1° vs L4: 34.8° ± 13.5°, p < 0.001). Postoperatively, there were no statistically significant differences in primary rod type, 2-rod versus multirod constructs, unilateral versus bilateral iliac fixation, number of levels fused, graft material, L5-S1 interbody fusion approach, and PI-lumbar lordosis mismatch. There were no significant differences between the cohorts in uni- versus bilateral pelvic fixation or type of fixation (iliac vs S2AI); however, patients who underwent L4 PSO had, on average, more pelvic screws placed (mean 1.9 ± 0.7 vs 1.5 ± 0.6, p = 0.002). L4 PSO resulted in larger postoperative L4-S1 segmental lordosis (37.2° ± 13.3° vs 21.4° ± 11.4°, p < 0.001) and reduced rates of postoperative low lordosis distribution index (20.0% vs 60.0%, p < 0.001). There were no significant differences in postoperative complication rates including CSF leak, iatrogenic dorsiflexion weakness, and 30- or 90-day readmissions. The L4 PSO cohort experienced lower DJP rates (6.7% vs 29.1%, p = 0.012), including hardware failure (3.3% vs 20.9%, p = 0.024) and pseudarthrosis (3.3% vs 25.6%, p = 0.008). Multivariate analysis found that multirod construct versus dual-rod configuration (OR 0.31, 95% CI 0.09-0.96) and L4 PSO (OR 0.18, 95% CI 0.02-0.80) were independently associated with decreased DJP rates. Age was also a risk factor for DJPs. The number of pelvic screws and pelvic screw fixation type did not predict DJPs.

CONCLUSIONS: In addition to multirod configurations, L4 PSO resulted in a lower rate of DJPs compared with L3 PSO. This result might be due to a more physiological distribution of lumbar lordosis with L4 PSO.

PMID:41931838 | DOI:10.3171/2025.10.SPINE25539

Phys Rev Lett. 2026 Mar 20;136(11):110201. doi: 10.1103/58vf-m1yx.

ABSTRACT

Mielnik’s cannonball argument uses the Zeno effect to argue that projective measurements for time of arrival are impossible. If one repeatedly measures the position of a particle (or a cannonball!) that has yet to arrive at a detector, the Zeno effect will repeatedly collapse its wave function away from it: the particle never arrives. Here we introduce quantum stroboscopic measurements where we accumulate statistics of projective position measurements, performed on different copies of the system at different times, to obtain a time-of-arrival distribution. We show that, under appropriate limits, this gives the same statistics as time measurements of conventional “always on” particle detectors that bypass Mielnik’s argument using nonprojective, weak continuous measurements. In addition to time of arrival, quantum stroboscopy can describe distributions of general time measurements. It can also be adapted to obtain the conditional probability distribution of arrival times, given that the particle was not previously detected at the detector.

PMID:41931808 | DOI:10.1103/58vf-m1yx

Phys Rev Lett. 2026 Mar 20;136(11):117101. doi: 10.1103/g468-nbm2.

ABSTRACT

The analysis of local minima in time series data and random landscapes is essential across numerous scientific disciplines, offering critical insights into system dynamics. Recently, Kundu et al. derived the exact distribution of the number of local minima for a broad class of Markovian symmetric walks [Phys. Rev. E 110, 024137 (2024)PRESCM2470-004510.1103/PhysRevE.110.024137]; however, many real-world systems are non-Markovian, typically due to interactions with possibly hidden degrees of freedom. This Letter investigates the statistical properties of local minima in discrete-time samples of fractional Brownian motion, a non-Markovian Gaussian process with stationary increments, widely used to model complex, anomalous diffusion phenomena. We derive a complete asymptotic characterization of the fluctuations of the number of local minima m_{N} in an N-step discrete-time fractional Brownian motion. We show that the fluctuations of m_{N} exhibit a sharp transition at the Hurst exponent H=3/4: for H≤3/4 they satisfy a central limit theorem with Gaussian limiting law, whereas for H>3/4 they converge to a non-Gaussian Rosenblatt process. The convergence at the process level gives us full statistical description at all times. We exemplify it on the covariance of the rescaled minima process, which displays two qualitatively distinct regimes matching Brownian and Rosenblatt covariances on either side of this threshold. Our analysis relies on a Hermite or Wick decomposition of the local-minimum indicator, which isolates a quadratic functional of an effective long-memory mode as the unique driver of the anomalous statistics. These results identify the count of local minima as a simple and robust diagnostic of long-range dependence in non-Markovian Gaussian processes, a conclusion supported by numerical simulations.

PMID:41931793 | DOI:10.1103/g468-nbm2

Phys Rev Lett. 2026 Mar 20;136(11):111401. doi: 10.1103/f74l-3c4y.

ABSTRACT

Because they are likely to accrete substantial amounts of interstellar gas, merging supermassive binary black holes are expected to be strong multimessenger sources, radiating gravitational waves, photons from thermal gas, and photons from relativistic electrons energized by relativistic jets. Here we report on a numerical simulation that covers the late inspiral, merger, and initial postmerger phase of such a system where both black holes have the same mass and spin, and both spin axes are parallel to the orbital angular momentum. The simulation incorporates both 3D general relativistic magnetohydrodynamics and numerical relativity. The thermal photon power during the late inspiral, merger, and immediate postmerger phases is drawn from strong shocks rather than dissipation of turbulence inside a smoothly structured accretion disk as typically found around accreting single black holes. We find that the thermal photon and jet Poynting flux outputs are closely related in time, and we posit a mechanism that enforces this relation. The power radiated in both photons and jets diminishes gradually as merger is approached, but jumps sharply at merger to a noisy plateau. Such a distinct lightcurve should aid efforts to identify supermassive black hole mergers, with or without accompanying gravitational wave detections.

PMID:41931783 | DOI:10.1103/f74l-3c4y

Phys Rev Lett. 2026 Mar 20;136(11):110402. doi: 10.1103/tqrb-4m9p.

ABSTRACT

We explore the joint measurability of incompatible qubit observables on ensembles of parallel and antiparallel spin-1/2 pairs. In parallel configuration, both spins are prepared in the same state, whereas in antiparallel case, each spin is paired with its flipped counterpart. We show that the antiparallel configuration uniquely enables exact simultaneous prediction of three mutually orthogonal spin components-an advantage not achievable with parallel states. Extending beyond three observables, we examine joint measurability for larger sets of spin measurements and further generalize our analysis to state configurations beyond the parallel and antiparallel cases. As we show, our results reveal a deep connection to the “mean King retrodiction task” proposed by Vaidman, Aharonov, and Albert and have implications for a cryptographic protocol introduced by Jeffrey Bub. We further demonstrate how the enhanced compatibility in the antiparallel configuration can facilitate efficient estimation of unknown measurement devices. Finally, we discuss prospects for experimentally realizing the enhanced measurement compatibility in antiparallel configuration by analyzing the effect on finite subensembles of states.

PMID:41931781 | DOI:10.1103/tqrb-4m9p

Neurology. 2026 Apr 28;106(8):e214858. doi: 10.1212/WNL.0000000000214858. Epub 2026 Apr 3.

ABSTRACT

BACKGROUND AND OBJECTIVES: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with a complex etiology. Although a range of genetic and lifestyle factors have been implicated, the potential role of environmental airborne pollution exposure is uncertain. This study examined the association between long-term ambient exposure to air pollutants and the incidence of ALS in UK Biobank participants.

METHODS: This prospective cohort study was based on the UK Biobank participants aged 40-69 years. The analytical sample comprised participants free of ALS at baseline and had complete data on air pollution exposure. Long-term exposure (2006-2021) to nitrogen dioxide (NO₂), nitrogen oxides (NO_X), fine particulate matter (PM_2.5; <2.5 µm), and coarse particulate matter (PM₁₀; <10 µm) was assessed using data from the UK Department for Environment, Food and Rural Affairs at a spatial resolution of 1 × 1 km. To evaluate the association between these pollutants and ALS risk, we used multivariable time-varying Cox proportional hazards models. Several sensitivity analyses were conducted to assess the robustness of the results. We also examined for gene-environment interaction stratified by C9orf72 status and UNC13A genotype.

RESULTS: Among the 501,308 participants with a mean age of 56.5 (SD 8.1) years at baseline, 272,764 (54.4%) were female. Over a median follow-up of 8.4 years, 687 individuals developed ALS. We did not observe any associations for any of the examined pollutants and ALS risk. Specifically, the hazard ratios per SD increment for PM₁₀, PM_2.5, NO_X, and NO₂ were 1.03 (95% CI 0.92-1.15), 1.00 (95% CI 0.88-1.14), 1.01 (95% CI 0.90-1.13), and 1.00 (95% CI 0.89-1.12), respectively. Individuals living in areas with the highest tertile of air pollutant exposure, compared with those in the lowest tertile, did not show a higher risk of ALS across any of the pollutants examined (p for trend >0.05). Restricted cubic spline analyses revealed no nonlinear associations between air pollution and ALS risk (all p for nonlinearity >0.05). These results remained robust in various subgroup and sensitivity analyses. No evidence of gene-environment interaction was found.

DISCUSSION: In this large population-based study with high statistical power, ambient air pollution was not a risk factor for the development of ALS.

PMID:41931746 | DOI:10.1212/WNL.0000000000214858

J Drugs Dermatol. 2026 Apr 1;25(4):316-323. doi: 10.36849/jdd.9441.

ABSTRACT

BACKGROUND: Janus kinase (JAK) inhibitors represent promising therapies for dermatologic conditions, including psoriasis, hidradenitis suppurativa (HS), atopic dermatitis (AD), systemic lupus erythematosus (SLE), and vitiligo. There are little data available evaluating the composition of research cohorts for this emerging treatment modality. Adequate racial representation in clinical trials is essential.

OBJECTIVE: To characterize the study populations of clinical trials for Janus kinase inhibitors for dermatologic indications.

METHODS: Clinical trials were identified from January 2000 to March 2025 through PubMed using the following keywords: “Janus kinase inhibitor,” “JAK inhibitor,” “alopecia areata,” “atopic dermatitis,” “hidradenitis suppurativa,” “systemic lupus erythematosus,” “systemic sclerosis,” “psoriasis,” and “vitiligo.” Additional trials were retrieved from ClinicalTrials.gov using the search term “JAK inhibitor.” Each trial was reviewed for demographic data, including race and ethnicity. Additional variables collected included Fitzpatrick skin type and quality-of-life measures. The distribution of race among trial participants was compared to the current US population and the condition-specific prevalence data where available.

RESULTS: Of 399 identified studies, 207 clinical trials were included in our analysis, including 57,112 study participants were analyzed. Among studies reporting race (57.5%), representation was predominantly White (75.1%), followed by Asian (13.2%), Black (6.6%), American Indian/Alaska Native (0.48%), Native Hawaiian (0.11%), and multiple races (0.43%). Underrepresentation was pronounced among Black participants in psoriasis (1.3%), SLE (1.0%), and vitiligo trials (5.1%), although higher in HS (27.9%). Representation in these trials significantly differed from the racial distribution of US patients with vitiligo (P=0.012) and AD (P=0.00088). White patients were overrepresented in vitiligo and AD trials (Pearson residual=1.06, 2.71), while Black patients were underrepresented in these trials (Pearson residual=-2.66, -2.14). Additionally, a minority of studies (28.98%) reported on QoL metrics, which are essential tools for measuring disease burden and impact on patients.

CONCLUSION AND RELEVANCE: Reporting on racial data, Fitzpatrick skin type, and quality of life measures is lacking in clinical trials for Janus kinase inhibitors. These factors play a key role in addressing comorbidities and mitigating disease burden. These findings highlight a need for improved recruitment strategies targeting underrepresented populations in dermatologic clinical research. &nbsp.

PMID:41931696 | DOI:10.36849/jdd.9441

J Drugs Dermatol. 2026 Apr 1;25(4):357-362. doi: 10.36849/jdd.9505.

ABSTRACT

BACKGROUND: Dermatologists remain unevenly distributed throughout the United States (US), leading to disparities in access to dermatologic care.

OBJECTIVE: To evaluate geographic variation in patient interest in dermatology services and compare it to dermatologist supply to identify areas of potential unmet need.

METHODS: An ecological, cross-sectional study was conducted using Google Trends data from 2004 to 2023 to assess relative search volume (RSV) for “dermatologist” across US states. RSV was normalized and combined with dermatologist density data from the AAMC to generate a Relative Demand Index (RDI) for each state. Spearman’s rank correlation assessed associations between RDI, dermatologist supply, urbanization, and population size.

RESULTS: States with high RDI, such as Alabama and Mississippi, had high patient interest but low dermatologist density, suggesting workforce shortages. Conversely, states like Massachusetts and the District of Columbia had low RDI and high provider density. RDI showed a strong inverse correlation with dermatologist density (rs = -0.76, P&lt;0.0001).

LIMITATIONS: This study relied on a keyword, Google-only search data, and assumed internet access. County-level nuances were not captured.

CONCLUSION: Significant geographic disparities in dermatologist availability and demand exist, highlighting the need for targeted workforce distribution strategies to ensure equitable access to dermatologic care. &nbsp.

PMID:41931691 | DOI:10.36849/jdd.9505