The social vulnerability metric (SVM) as a new tool for public health

Objective

To derive and validate a new ecological measure of the social determinants of health (SDoH), calculable at the zip code or county level.

Data Sources and Study Setting

The most recent releases of secondary, publicly available data were collected from national U.S. health agencies as well as state and city public health departments.

Study Design

The Social Vulnerability Metric (SVM) was constructed from U.S. zip-code level measures (2018) from survey data using multidimensional Item Response Theory and validated using outcomes including all-cause mortality (2016), COVID-19 vaccination (2021), and emergency department visits for asthma (2018). The SVM was also compared with the existing Centers for Disease Control and Prevention's Social Vulnerability Index (SVI) to determine convergent validity and differential predictive validity.

Data Collection/Extraction Methods

The data were collected directly from published files available to the public online from national U.S. health agencies as well as state and city public health departments.

Principal Findings

The correlation between SVM scores and national age-adjusted county all-cause mortality was r = 0.68. This correlation demonstrated the SVM's robust validity and outperformed the SVI with an almost four-fold increase in explained variance (46% vs. 12%). The SVM was also highly correlated (r ≥ 0.60) to zip-code level health outcomes for the state of California and city of Chicago.

Conclusions

The SVM offers a measurement tool improving upon the performance of existing SDoH composite measures and has broad applicability to public health that may help in directing future policies and interventions. The SVM provides a single measure of SDoH that better quantifies associations with health outcomes.     

Diagnostic accuracy of laboratory and ultrasound findings in patients with a non-visualized appendix

Ultrasound (US) and laboratory testing are initial diagnostic tests for acute appendicitis. A diagnostic dilemma develops when the appendix is not visualized on US. Objective: To determine if specific US findings and/or laboratory results predict acute appendicitis when the appendix is not visualized. Methods: A prospective study was conducted on children (birth-18?yrs) presenting to the pediatric emergency department with suspected acute appendicitis who underwent right lower quadrant US.Children with previous appendectomy, US at another facility, or eloped were excluded. US findings analyzed: inflammatory changes, right lower quadrant and lower abdominal fluid, tenderness during US exam and lymph nodes. Diagnoses were confirmed via surgical pathology. Results 1252 subjects were enrolled, 60.8% (762) had appendix visualized and 39.1% (490) did not. In children where the appendix was not seen, 6.7% [33] were diagnosed with appendicitis. Among patients with a non-visualized appendix, the likelihood of appendicitis was significantly greater if: inflammatory changes in the RLQ (OR 18.0, 95% CI 4.5–72.1), CRP >0.5?mg/dL (OR 2.64, 95% CI 1.0–6.8), or WBC?>?10 (OR 4.36, 95% CI 1.66–11.58). Duration of abdominal pain >3?days was significantly less likely associated with appendicitis in this model (OR 0.34, 95% CI 0.003–0.395). Combined, the absence inflammatory changes, CRP?<?0.5?mg/dL, WBC?<?10, and pain, ≤3?days had a NPV of 94.0%. Conclusion When the appendix is not visualized on US, predictors for appendicitis include the presence of inflammatory changes in the RLQ, an elevated WBC/CRP and abdominal pain <3?days.