C. Victor Spain

It’s Not the Heat, It’s the Humidity: Wet Weather Increases Legionellosis Risk in the Greater Philadelphia Metropolitan Area

BACKGROUND Legionella species are abundant in the environment and are increasingly recognized as a cause of severe pneumonia. Increases in cases of community-acquired legionellosis in the greater Philadelphia metropolitan area (GPMA) led to concern that changing environmental factors could influence occurrence of disease. METHODS We evaluated the association between weather patterns and occurrence of legionellosis in the GPMA, using both traditional Poisson regression analysis and a case-crossover study approach. The latter approach controls for seasonal factors that could confound the relationship between weather and occurrence of disease and permits the identification of acute weather patterns associated with disease. RESULTS A total of 240 cases of legionellosis were reported between 1995 and 2003. Cases occurred with striking summertime seasonality. Occurrence of cases was associated with monthly average temperature (incidence rate ratio [IRR] per degree Celsius, 1.07 [95% confidence interval [CI], 1.05-1.09]) and relative humidity (IRR per 1% increase in relative humidity, 1.09 [95% CI, 1.06-1.12]) by Poisson regression analysis. However, case-crossover analysis identified an acute association with precipitation (odds ratio [OR], 2.48 [95% CI, 1.30-3.12]) and increased humidity (OR per 1% increase in relative humidity, 1.08 [95% CI, 1.05-1.11]) 6-10 days before occurrence of cases. A significant dose-response relationship for occurrence of cases was seen with both precipitation and increased humidity. CONCLUSIONS Although, in the GPMA, legionellosis occurred predominantly during summertime, the acute occurrence of disease is best predicted by wet, humid weather. This finding is consistent with the current understanding of the ecological profile of this pathogen and supports the contention that sporadic legionellosis occurs through contamination of water sources.

Comparative effectiveness of patient education methods for type 2 diabetes: a randomized controlled trial.

BACKGROUND Group education for patients with suboptimally controlled diabetes has not been rigorously studied. METHODS A total of 623 adults from Minnesota and New Mexico with type 2 diabetes and glycosylated hemoglobin (HbA(1c)) concentrations of 7% or higher were randomized to (1) group education (using the US Diabetes Conversation Map program), (2) individual education, or (3) usual care (UC; ie, no assigned education). Both education methods covered content as needed to meet national standards for diabetes self-management education and were delivered through accredited programs from 2008 to 2009. General linear mixed-model methods assessed patient-level changes between treatment groups in mean HbA(1c) levels from baseline to follow-up at 6.8 months. Secondary outcomes included mean change in general health status (Medical Outcomes Study 12-Item Short Form Health Survey [SF-12]), Problem Areas in Diabetes (PAID), Diabetes Self-Efficacy (DES-SF), Recommended Food Score (RFS), and Physical Activity (PA, min/wk). RESULTS Mean HbA(1c) concentration decreased in all groups but significantly more with individual (-0.51%) than group education (-0.27%) (P = .01) and UC (-0.24%) (P = .01). The proportion of subjects with follow-up HbA(1c) concentration lower than 7% was greater for individual education (21.2%) than for group (13.9%) and UC (12.8%) (P = .03). Compared with UC, individual education (but not group) improved SF-12 physical component score (+1.88) (P = .04), PA (+42.95 min/wk) (P = .03), and RFS (+0.63) (P = .05). Compared with group education, individual education reduced PAID (-3.62) (P = .02) and increased self-efficacy (+0.1) (P = .04). CONCLUSIONS Individual education for patients with established suboptimally controlled diabetes resulted in better glucose control outcomes than did group education using Conversation Maps. There was also a trend toward better psychosocial and behavioral outcomes with individual education. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00652509.

Let the sun shine in: effects of ultraviolet radiation on invasive pneumococcal disease risk in Philadelphia, Pennsylvania.

BackgroundStreptococcus pneumoniae is a common cause of community acquired pneumonia and bacteremia. Excess wintertime mortality related to pneumonia has been noted for over a century, but the seasonality of invasive pneumococcal disease (IPD) has been described relatively recently and is poorly understood. Improved understanding of environmental influence on disease seasonality has taken on new urgency due to global climate change.MethodsWe evaluated 602 cases of IPD reported in Philadelphia County, Pennsylvania, from 2002 to 2007. Poisson regression models incorporating seasonal smoothers were used to identify associations between weekly weather patterns and case counts. Associations between acute (day-to-day) environmental fluctuations and IPD occurrence were evaluated using a case-crossover approach. Effect modification across age and sex strata was explored, and meta-regression models were created using stratum-specific estimates for effect.ResultsIPD incidence was greatest in the wintertime, and spectral decomposition revealed a peak at 51.0 weeks, consistent with annual periodicity. After adjustment for seasonality, yearly increases in reporting, and temperature, weekly incidence was found to be associated with clear-sky UV index (IRR per unit increase in index: 0.70 [95% CI 0.54-0.91]). The effect of UV index was highest among young strata and decreased with age. At shorter time scales, only an association with increases in ambient sulphur oxides was linked to disease risk (OR for highest tertile of exposure 0.75, 95% CI 0.60 to 0.93).ConclusionWe confirmed the wintertime predominance of IPD in a major urban center. The major predictor of IPD in Philadelphia is extended periods of low UV radiation, which may explain observed wintertime seasonality. The mechanism of action of diminished light exposure on disease occurrence may be due to direct effects on pathogen survival or host immune function via altered 1,25-(OH)2-vitamin-D metabolism. These findings may suggest less diminution in future IPD risk with climate change than would be expected if wintertime seasonality was driven by temperature.

Validity of the Adherence Estimator in the Prediction of 9-Month Persistence With Medications Prescribed for Chronic Diseases: A Prospective Analysis of Data From Pharmacy Claims

OBJECTIVE The aim of this article was to assess the predictive validity of the Adherence Estimator--a 3-item instrument designed to estimate a patients propensity to adhere to medications prescribed for chronic disease. METHODS The Adherence Estimator was a 3-item part of a larger survey mailed to adults aged >or=40 years who had a qualifying index prescription filled in June 2008. A qualifying prescription was defined as one for a medication indicated for the treatment of 1 of 5 chronic diseases (cardiovascular disease, dyslipidemia [lipid-lowering drugs], diabetes [oral antihyperglycemics], osteoporosis [oral bisphosphonates], or asthma). Outcomes were compared between the adherence risk groups derived from the Adherence Estimator (low risk = score of 0, medium risk = score of 2-7, and high risk = score of 8-36). Treatment persistence over a period of 9 months was measured using pharmacy claims data. The primary outcome was the median proportion of days covered (PDC) by >or=1 medication during the first 9 months after the index fill. Secondary outcomes included adherence to the index medication, defined as PDC dichotomized to >or=0.80 or <0.80; rate of obtaining a second fill within 30 days of the index fill; and medication possession ratio (MPR) for refill adherence. RESULTS There were 1676 usable responses. Ages ranged from 40 to 88 years, with a mean of 64.6 years. Almost two thirds (1076/1676 [64.2%]) of the sample were female, and 1483/1676 (88.5%) were white. Statistically significant associations for all 3 pairwise comparisons (low vs medium risk, low vs high risk, and medium vs high risk) were observed between the Adherence Estimator risk groups for: (1) median PDC (0.655, 0.598, and 0.484 in the low-, medium-, and high-risk groups, respectively [all, false discovery rate [FDR] <0.05]); (2) PDC categorized (293/711 [41.21%], 200/588 [34.01%], and 105/377 [27.85%] [all, FDR <0.05]); and (3) rate of obtaining a second fill for the index medication within 30 days (489/711 [68.78%], 374/588 [63.61%], and 207/377 [54.91%] [all, FDR <0.05]). The low- and high-risk groups differed from one another on: (1) persistence with the index medication at 9 months (265/711 [37.27%] and 95/377 [25.20%]); (2) persistence with >1 medication at 9 months (291/711 [40.93%] and 108/377 [28.65%]); and (3) obtaining a second fill for any medication within 30 days (501/711 [70.46%] and 219/377 [59.09%]) (all, P < 0.05). The low- and high-risk groups differed significantly from one another in MPR for refill adherence (0.912 vs 0.866). Results observed within diseases mirrored those for the total sample, but with less precision. CONCLUSION In the present analysis of the validity of the Adherence Estimator in predicting adherence, baseline propensity to adhere to medications prescribed for chronic diseases was statistically associated with several measures of adherence and persistence, as derived from pharmacy claims data, over a 9-month period.

Determining Risk Markers for Gonorrhea and Chlamydial Infection and Reinfection Among Adolescents in Public High Schools

Background: In response to high adolescent rates of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC), Philadelphia began screening in all public high schools in 2003. Methods: Data from 14,862 students who tested more than once in the Philadelphia High School STD Screening Program (PHSSSP) during the 2002–2006 school years were analyzed for factors associated with CT and GC infection. Multivariable Cox proportional hazards models and logistic regression models were constructed to identify characteristics associated with measured STD rates. A secondary analysis assessed short-term reinfection rates among participants retesting within the same school year. Results: In the primary analysis, over multiple years, the unadjusted female CT/GC rate was more than double that in males (6.0 vs. 2.4 cases per 100 person-years, respectively). Among students with a baseline positive, males had a higher rate than females (19.9 vs. 17.7 cases per 100 person-years, respectively). Among students with a positive test result, 13.6% were reinfected within the same school year. Females with named partners not treated had a higher reinfection rate than all others (85.5 vs. 40.1–45.2 cases per 100 person-years, respectively). Conclusions: Clinicians and screening programs that offer STD testing to urban high school students, regardless of gender, should encourage those with a prior STD history to test more frequently. Clinicians should work with infected patients, especially females, to ensure their partners are treated.

Association between enhanced screening for Chlamydia trachomatis and Neisseria gonorrhoeae and reductions in sequelae among women.

PURPOSE Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) are typically asymptomatic, but, if untreated, can lead to sequelae including pelvic inflammatory disease (PID) and ectopic pregnancy. The objective was to describe trends of these sequelae in Philadelphia after implementing citywide screening in a high-morbidity population (>6% positivity). METHODS In this ecologic study, which used data from 1996 to 2007, multivariable linear regression analysis was used to assess the association between the number of annual CT/GC screening tests by gender and the number of women aged 14-30 years hospitalized for PID or ectopic pregnancy. A standardized hospitalization database provided the number of admissions with a discharge diagnosis of PID or ectopic pregnancy. Positive CT/GC laboratory results reported by hospitals and emergency departments (EDs) were used as a proxy for outpatient PID. RESULTS Between 1996 and 2007, CT/GC screening increased by 188%, whereas declines were noted in hospitalized PID cases (36%, -173 cases), ectopic pregnancy (38%, -119 cases), and ED-diagnosed CT/GC cases (39%, -727 cases). Screening 10,000 females for CT/GC corresponded with 26.1 fewer hospitalized PID cases (95% confidence interval 11.2-41.1), whereas screening 10,000 males corresponded to 10.4 (95% CI: 2.6-18.2) fewer cases. Although male screening was not significantly associated with ectopic pregnancy, screening 10,000 females was associated with 28.6 fewer ectopic pregnancies (95% CI: 7.4-49.8). CONCLUSIONS This ecologic analysis found a correlation between large-scale CT/GC screening in a high-morbidity population and reductions in hospitalized PID, ectopic pregnancies, and ED-diagnosed CT/GC.

Environmental Exposures and Invasive Meningococcal Disease: An Evaluation of Effects on Varying Time Scales

Invasive meningococcal disease (IMD) is an important cause of meningitis and bacteremia worldwide. Seasonal variation in IMD incidence has long been recognized, but mechanisms responsible for this phenomenon remain poorly understood. The authors sought to evaluate the effect of environmental factors on IMD risk in Philadelphia, Pennsylvania, a major urban center. Associations between monthly weather patterns and IMD incidence were evaluated using multivariable Poisson regression models controlling for seasonal oscillation. Short-term weather effects were identified using a case-crossover approach. Both study designs control for seasonal factors that might otherwise confound the relation between environment and IMD. Incidence displayed significant wintertime seasonality (for oscillation, P < 0.001), and Poisson regression identified elevated monthly risk with increasing relative humidity (per 1% increase, incidence rate ratio = 1.04, 95% confidence interval: 1.004, 1.08). Case-crossover methods identified an inverse relation between ultraviolet B radiation index 1–4 days prior to onset and disease risk (odds ratio = 0.54, 95% confidence interval: 0.34, 0.85). Extended periods of high humidity and acute changes in ambient ultraviolet B radiation predict IMD occurrence in Philadelphia. The latter effect may be due to decreased pathogen survival or virulence and may explain the wintertime seasonality of IMD in temperate regions of North America.

Environmental determinants of campylobacteriosis risk in Philadelphia from 1994 to 2007.

Campylobacter species infections are a common cause of acute gastroenteritis, and may uncommonly be complicated by renal, neurological, and rheumatologic sequelae. Although excess summertime campylobacteriosis has been observed, environmental mechanisms driving disease seasonality are poorly understood. We sought to evaluate the relationship between environmental factors and campylobacteriosis risk in a major North American metropolitan area. We evaluated 1532 cases of campylobacteriosis reported in Philadelphia between 1994 and 2007. We constructed Poisson regression models with oscillatory smoothers, and also used case-crossover design, to evaluate the associations between environmental exposures and disease risk on weekly and daily time scales. Both methods control for confounding by seasonally oscillating environmental factors. Incidence was greatest in June and July, with annual periodicity. Weekly incidence was associated with increasing relative humidity, (incidence rate ratio (IRR) per % 1.017, 95% CI 1.008–1.025), temperature (IRR per °C 1.041, 95% CI 1.011–1.072), and decreasing Delaware River temperature during the same week (IRR per °C 0.922, 95% CI 0.883–0.962), and at 4-week lags (IRR per °C 0.953, 95% CI 0.919–0.990). No acute associations were identified in case-crossover analyses. Our findings affirm the summertime seasonality of campylobacteriosis in Philadelphia, and the link between warm, humid weather and disease risk. However, the link between low river temperatures and enhanced campylobacteriosis risk in humans described here is novel, consistent with known links between watershed temperature and Campylobacter survival, and implicates local watersheds as epidemiologically important reservoirs for foodborne pathogens.

The Philadelphia High-School STD Screening Program: key insights from dynamic transmission modeling.

Background: The Philadelphia high-school STD Screening Program (PHSSP) represents an innovative approach to screening-based control of Chlamydia trachomatis infection. The program has been associated with significant reductions in Chlamydia trachomatis prevalence in young females in Philadelphia. We sought to assess program cost-effectiveness in a manner that allowed us to quantify the impact of including males students in the screened population. Methods: We created a dynamic transmission model using a susceptible-infectious-resistant-susceptible framework. The model was parameterized using PHSSP program data, supplemented by available data from the medical and public health literature, and was used to project the impact of screening on disease burden, quality adjusted survival, and costs. Results: A well-calibrated model suggests that high-school based screening is highly cost-effective in the Philadelphia context. Five important insights are gained through dynamic transmission modeling of the PHSSP: (i) the importance of screening males can be appreciated using a dynamic transmission model; (ii) the attractiveness of screening males is inversely related to equilibrium prevalence in males; (iii) including males enhances both effectiveness and economic attractiveness of screening; (iv) rebound in prevalence does not greatly diminish the cost-effectiveness of screening; and (v) increasing program expenditures via increased screening coverage decreases net societal costs, due to diminished disease transmission. Conclusions: The current PHSSP is highly cost-effective relative to other commonly accepted interventions. Effectiveness and cost-effectiveness of this program are enhanced by including males. This, and other important attributes of the program, is best appreciated when a dynamic transmission model is used for program evaluation.

A comparative analysis of recruitment methods used in a randomized trial of diabetes education interventions.

Recruitment methods heavily impact budget and outcomes in clinical trials. We conducted a post-hoc examination of the efficiency and cost of three different recruitment methods used in Journey for Control of Diabetes: the IDEA Study, a randomized controlled trial evaluating outcomes of group and individual diabetes education in New Mexico and Minnesota. Electronic databases were used to identify health plan members with diabetes and then one of the following three methods was used to recruit study participants: 1. Minnesota Method 1--Mail only (first half of recruitment period). Mailed invitations with return-response forms. 2. Minnesota Method 2--Mail and selective phone calls (second half of recruitment period). Mailed invitations with return-response forms and subsequent phone calls to nonresponders. 3. New Mexico Method 3--Mail and non-selective phone calls (full recruitment period): Mailed invitations with subsequent phone calls to all. The combined methods succeeded in meeting the recruitment goal of 623 subjects. There were 147 subjects recruited using Minnesotas Method 1, 190 using Minnesotas Method 2, and 286 using New Mexicos Method 3. Efficiency rates (percentage of invited patients who enrolled) were 4.2% for Method 1, 8.4% for Method 2, and 7.9% for Method 3. Calculated costs per enrolled subject were