Baltimore Metropolitan Region Research Articles

Climatological Analyses of Thunderstorms and Flash Floods in the Baltimore Metropolitan Region

Abstract The climatology of thunderstorms and flash floods in the Baltimore, Maryland, metropolitan region is examined through analyses of cloud-to-ground (CG) lightning observations from the National Lightning Detection Network (NLDN) and discharge observations from 11 U.S. Geological Survey (USGS) stream gauging stations. A point process framework is used for analyses of CG lightning strikes and the occurrences of flash floods. Analyses of lightning strikes as a space–time point process focus on the mean intensity function, from which the seasonal, diurnal, and spatial variation in mean lightning frequency are examined. Important elements of the spatial variation of mean lightning frequency are 1) initiation of thunderstorms along the Blue Ridge, 2) large variability of lightning frequency around the urban cores of Baltimore and Washington D.C., and 3) decreased lightning frequency over the Chesapeake Bay and Atlantic Ocean. Lightning frequency has a sharp seasonal maximum around mid-July, and the diurnal cycle of lightning frequency peaks between 2100 and 2200 UTC with a frequency that is more than an order of magnitude larger than the minimum frequency at 1200 UTC. The seasonal and diurnal variation of flash flood occurrence in urban streams of Baltimore mimics the seasonal and diurnal variation of lightning. The peak of the diurnal frequency of flash floods in Moores Run, a 9.1-km2 urban watershed in Baltimore City, occurs at 2200 UTC. Analyses of the lightning and flood peak data also show a close link between the occurrence of major thunderstorms systems and flash flooding on a regional scale.

Costs of HIV medical care in the era of highly active antiretroviral therapy.

In the USA, Medicaid is the principal payer of the health care costs of patients with HIV infection. We wished to determine how the costs to Medicaid of patients in Maryland infected with HIV have changed in the setting of highly active antiretroviral treatment. Observational cohort study. Analysis of combined economic and clinical data of patients from the Johns Hopkins HIV Service, the provider of primary and sub-specialty care for a majority of HIV-infected patients in the Baltimore metropolitan region. All patients were enrolled in Medicaid and received care longitudinally in Maryland from 1 January 1995 through 31 December 1997. Monthly Medicaid payments were calculated for all inpatient and outpatient services by fiscal year, CD4 cell count, and use of protease inhibitors. For inpatients with a CD4 cell count < or = 50 x 10(6) cells/l, the total health care average monthly payments remained unchanged ($2629 in 1995, $2585 in 1997). Total mean monthly payments increased for those with a CD4 cell count > 50 x 10(6) cells/l (CD4 cell count 50-200 x 10(6) cells/l, $1172 in 1995 and $1615 in 1997, P < 0.05; CD4 cell count 201-500 x 10(6) cells/l, $1078 in 1995 and $1305 in 1997, P < 0.05). However, when data were stratified according to use of a protease inhibitor-containing regimen (used during approximately 50% of follow-up time in 1996-1997) it was found that hospital inpatient payments decreased significantly in all CD4 strata for patients on a protease inhibitor-containing regimen whereas pharmacy payments increased significantly. Inpatient payments associated with treating opportunistic illness were lower in 1996-1997 for patients receiving protease inhibitor therapy compared with those not receiving protease inhibitors. On balance, total health care payments tended to be slightly lower for patients receiving a protease inhibitor regimen. Although protease inhibitor-containing antiretroviral regimens are being used by only about half of our Medicaid-insured patients, when they are used, there are significantly lower hospital inpatient and community care costs, as well as lower costs associated with the treatment of opportunistic illness. Even with the concurrent increase in their pharmacy costs, total health care costs were stable or slightly lower for these patients. We believe this is a favorable result suggesting a good clinical value being achieved without an increase in costs.

Costs to Medicaid of Advancing Immunosuppression in an Urban HIV-Infected Patient Population in Maryland

Human immunodeficiency virus (HIV) infection is increasingly an urban disease in the United States, and Medicaid is the principal payer of the health care costs of patients with HIV. We wished to determine the costs to Medicaid of patients in Maryland infected with HIV as immunosuppression progresses, and to determine how costs varied by demographic characteristics of the patient. We analyzed combined economic and clinical data in patients from the Johns Hopkins HIV Service, the provider of primary and specialty care for a majority of HIV-infected patients in the Baltimore metropolitan region. All patients were enrolled in Medicaid and received care longitudinally in Maryland from July 1992 to June 1995. Monthly Medicaid payments were calculated for all inpatient and outpatient services by sex, race, age, use of injecting drugs, CD4+ count (>500, 201-500, 51-200, < or =50 cells/mm3), several opportunistic diseases, and death. Lifetime costs were also calculated by use of a Markov simulation. During 13,174 person-months of follow-up in 606 patients, a total of $18,223,700 in Medicaid payments was made. Mean monthly payments ranged from $2,436 (SE $171) for patients with CD4+ counts < or =50 cells/mm3 to $1,015 (SE $177) for patients with CD4+ counts >500 cells/mm3. Mean monthly inpatient costs ranged from $1,355 (SE $131) for CD4+ counts < or =50 cells/mm3 and $617 (SE $164) for CD4- counts >500 cells/mm3. For those with CD4+ counts < or =50 cells/mm3, outpatient pharmacy costs averaged $515 (SE $57) monthly, second only to inpatient costs. In bivariate analysis, costs were significantly higher (p = .013) in men (mean $1696; SE $126) than in women (mean $1,208; SE $101), though the difference was not significant with multivariate adjustment. Cytomegalovirus retinitis was the most costly opportunistic disease, with mean monthly costs of $7,825 (SE $1,141) within the 6 mo after diagnosis. Within 6 mo of death, mean monthly costs are $4,600 (SE $424). Lifetime costs for treating an HIV-infected patient who presents with a CD4+ count >500 cells/mm3 are $133,500 over 8.3 years of life. We concluded that in the clinic where the analysis was done, average costs to Medicaid of treating patients increase more than two-fold as the CD4+ count declines from >500 cells/mm3 to < or =50 cells/mm3. Interventions that decrease hospitalization, opportunistic disease, and the costs of terminal care may be most likely to decrease overall costs. Demographic patient characteristics do not affect costs significantly when access to care is comparable.