Effect of Instrument Lubricant on Mechanical Properties of Restorative Composite.

OBJECTIVES: Using a wetting resin or adhesive system as an instrument lubricant when placing composite layers is commonly practiced to improve handling. This study investigated whether instrument lubricants affected strength, stiffness, or hardness. METHODS: Composite beams (TPH Spectra) were fabricated using a stainless steel mold (25×2.5×2 mm) in two steps, where the second half (12.5 mm) was added and cured against a cured first half (n=15). The composite surface at the open end of the first half was smoothed using an instrument lubricated with wetting resin (Ultradent) or universal adhesive (ScotchBond Universal), enough to prevent sticking, or without lubrication. An additional beam of each group was characterized using scanning electron microscopy. Monolithic specimens were also fabricated. After 24 hour storage (37°C, 100% humidity), the beams' flexural strength and stiffness were determined by four-point bending. Vickers surface hardness was measured on 24-hour composite samples in 2 mm deep acrylic cavities, cured after the surface was smoothed with the two instrument lubricants or no lubricant (n=10). Hardness was remeasured after finishing with a series of contouring and polishing discs. Data were statistically analyzed using ANOVA followed by Student-Newman-Keuls post hoc test at 0.05 significance level. RESULTS: There were significant differences (p<0.001) in flexural strength and stiffness among groups. While strength and stiffness were not affected by using a wetting resin as instrument lubricant, use of a universal adhesive increased strength and stiffness significantly, achieving monolithic values. Scanning electron micrographs showed less porosities at the interface when using instrument lubricants. Surface hardness was significantly reduced in groups in which instrument lubricants were used, but finishing/polishing restored original hardness (p<0.001). CONCLUSIONS: Lubricating an instrument with a wetting agent did not adversely affect physical or surface properties, provided the surface was finished and polished. If a universal adhesive was used as lubricant, the strength and stiffness of a layered composite could be increased, reaching monolithic values.

Allele frequency spectrum of known ankylosing spondylitis associated variants in a Swedish population.

Objective: The genetic predisposition to ankylosing spondylitis (AS) has been most widely studied in cohorts with European ancestry. However, within Europe, disease prevalence is higher in Sweden. Given this, we aimed to characterize known AS susceptibility variants in a homogeneous Swedish data set, assessing reproducibility and direction of effect.Method: The power to detect association within an existing Swedish targeted sequencing study (381 controls; 310 AS cases) was examined, and a set of published associations (n = 151) was intersected with available genotypes. Association to disease was calculated using logistic regression accounting for population structure, and HLA-B27 status was determined with direct polymerase chain reaction genotyping.Results: The cases were found to be 92.3% HLA-B27 positive, with the data set showing ≥ 80% predictive power to replicate associations, with odds ratios ≥ 1.6 over a range of allele frequencies (0.1-0.7). Thirty-four markers, representing 23 gene loci, were available for investigation. The replicated variants tagged MICA and IL23R loci (p < 1.47 × 10-3), with variable direction of effect noted for gene loci IL1R1 and MST1.Conclusion: The Swedish data set successfully replicated both major histocompatibility complex (MHC) and non-MHC loci, and revealed a different replication pattern compared to discovery data sets. This was possibly due to population demographics, including HLA-B27 frequency and measured comorbidities.

Extended exome sequencing identifies BACH2 as a novel major risk locus for Addison's disease.

BACKGROUND: Autoimmune disease is one of the leading causes of morbidity and mortality worldwide. In Addison's disease, the adrenal glands are targeted by destructive autoimmunity. Despite being the most common cause of primary adrenal failure, little is known about its aetiology. METHODS: To understand the genetic background of Addison's disease, we utilized the extensively characterized patients of the Swedish Addison Registry. We developed an extended exome capture array comprising a selected set of 1853 genes and their potential regulatory elements, for the purpose of sequencing 479 patients with Addison's disease and 1394 controls. RESULTS: We identified BACH2 (rs62408233-A, OR = 2.01 (1.71-2.37), P = 1.66 × 10-15 , MAF 0.46/0.29 in cases/controls) as a novel gene associated with Addison's disease development. We also confirmed the previously known associations with the HLA complex. CONCLUSION: Whilst BACH2 has been previously reported to associate with organ-specific autoimmune diseases co-inherited with Addison's disease, we have identified BACH2 as a major risk locus in Addison's disease, independent of concomitant autoimmune diseases. Our results may enable future research towards preventive disease treatment.

Diagnostic value of abdominal drainage in individual risk assessment of pancreatic fistula following pancreaticoduodenectomy.

BACKGROUND: The use of prophylactic abdominal drainage following pancreaticoduodenectomy (PD) is controversial as its therapeutic value is uncertain. However, the diagnosis of postoperative pancreatic fistula (POPF), the main cause of PD-associated morbidity, is often based on drain pancreatic amylase (DPA) levels. The aim of this study was to assess the predictive value of DPA, plasma pancreatic amylase (PPA) and serum C-reactive protein (CRP) for diagnosing POPF after PD. METHODS: Patients undergoing PD with prophylactic drainage between 2008 and 2012 were studied prospectively. DPA, PPA and CRP levels were obtained daily. Differences between groups with clinically relevant POPF (International Study Group on Pancreatic Fistula (ISGPF) grade B/C) and without clinically relevant POPF (no POPF or ISGPF grade A) were evaluated. Receiver operating characteristic (ROC) analyses were performed to determine the value of DPA, PPA and CRP in prediction of POPF. Risk profiles for clinically relevant POPF were constructed and related to the intraoperative pancreatic risk assessment. RESULTS: Fifty-nine (18.7 per cent) of 315 patients developed clinically relevant POPF. DPA, PPA and CRP levels on postoperative day (POD) 1-3 differed significantly between the study groups. In predicting POPF, the DPA level on POD 1 (cut-off at 1322 units/l; odds ratio (OR) 24.61, 95 per cent confidence interval 11.55 to 52.42) and POD 2 (cut-off at 314 units/l; OR 35.45, 14.07 to 89.33) was superior to that of PPA on POD 1 (cut-off at 177 units/l; OR 13.67, 6.46 to 28.94) and POD 2 (cut-off at 98 units/l; OR 16.97, 8.33 to 34.59). When DPA was combined with CRP (cut-off on POD 3 at 202 mg/l; OR 16.98, 8.43 to 34.21), 90.3 per cent of postoperative courses could be predicted correctly (OR 44.14, 16.89 to 115.38). CONCLUSION: The combination of serum CRP and DPA adequately predicted the development of clinically relevant pancreatic fistula following PD.

Self-report compared to electronic medical record across eight adult vaccines: do results vary by demographic factors?

Immunizations are crucial to the prevention of disease, thus, having an accurate measure of vaccination status for a population is an important guide in targeting prevention efforts. In order to comprehensively assess the validity of self-reported adult vaccination status for the eight most common adult vaccines we conducted a survey of vaccination receipt and compared it to the electronic medical record (EMR), which was used as the criterion standard, in a population of community-dwelling patients in a large healthcare system. In addition, we assessed whether validity varied by demographic factors. The vaccines included: pneumococcal (PPSV), influenza (Flu), tetanus diphtheria (Td), tetanus diphtheria pertussis (Tdap), Human Papilloma Virus (HPV), hepatitis A (HepA), hepatitis B (HepB) and herpes zoster (shingles). Telephone surveys were conducted with 11,760 individuals, ≥18, half with documented receipt of vaccination and half without. We measured sensitivity, specificity, positive and negative predictive value, net bias and over- and under-reporting of vaccination. Variation was found across vaccines, however, sensitivity and specificity did not vary substantially by either age or race/ethnicity. Sensitivity ranged between 63% for HepA to over 90% (tetanus, HPV, shingles and Flu). Hispanics were 2.7 times more likely to claim receipt of vaccination compared to whites. For PPSV and Flu those 65+ had low specificity compared to patients of younger ages while those in the youngest age group had lowest specificity for HepA and HepB. In addition to racial/ethnic differences, over-reporting was more frequent in those retired and those with household income less than $75,000. Accurate information for vaccination surveillance is important to estimate progress toward vaccination coverage goals and ensure appropriate policy decisions and allocation of resources for public health. It was clear from our findings that EMR and self-report do not always agree. Finding approaches to improve both EMR data capture and patient awareness would be beneficial.

Safety of zoster vaccine in adults from a large managed-care cohort: a Vaccine Safety Datalink study.

OBJECTIVES: The aim of this study was to examine a large cohort of adults who received the zoster vaccine for evidence of an increased risk of prespecified adverse events requiring medical attention. DESIGN: Two self-comparison approaches, including a case-centred approach and a self-controlled case series (SCCS) analysis were used. SETTING: Eight managed-care organizations participating in the Vaccine Safety Datalink project in the United States. SUBJECTS: A total of 193 083 adults aged 50 and older receiving a zoster vaccine from 1 January 2007 to 31 December 2008 were included. MAIN OUTCOME MEASURES: Prespecified adverse events were identified by aggregated International Classification of Diseases, Ninth Revision (ICD-9) codes in automated health plan datasets. RESULTS: The risk of allergic reaction was significantly increased within 1-7 days of vaccination [relative risk = 2.13, 95% confidence interval (CI): 1.87-2.40 by case-centred method and relative rate = 2.32, 95% CI: 1.85-2.91 by SCCS]. No increased risk was found for the following adverse event groupings: cerebrovascular events; cardiovascular events; meningitis; encephalitis; and encephalopathy; and Ramsay-Hunt syndrome and Bell's palsy. CONCLUSIONS: The results of this study support the findings from the prelicensure clinical trials, providing reassurance that the zoster vaccine is generally safe and well-tolerated with a small increased risk of allergic reactions in 1-7 days after vaccination.

An original knee arthrodesis technique combining external fixator with Steinman pins direct fixation.

INTRODUCTION: Knee arthrodesis may be the last possible option for infected total knee arthroplasty (TKA) patients and in revision cases involving severe bone loss and/or extensor mechanism damages. Success in these situations depends on achieving good fixation assembly stability. We report bone fusion results using a fixation technique combining cross-pinning by two Steinman pins with a single-frame external fixator. Remission of infection at long-term follow-up was an additional criteria assessed for those cases initially treated for sepsis. HYPOTHESIS: This fixation modality improves fusion rates. PATIENTS AND METHODS: In six of this series of eight patients (mean age: 59 years), surgery was performed in a context of infection: five cases of infected TKA, and one case of septic arthritis. In the other two cases, arthrodesis was respectively indicated for a severe post-traumatic stiffness compounded by extensor system rupture and for a fracture combined to a complete mechanical implant loosening. In three of the six infection cases, arthrodesis was performed as a single-stage procedure. All patients were operated on using the same technique: primary arthrodesis site stabilization by frontal cross-pinning with two Steinman pins, followed by installation of a sagittal external fixator frame. Results were assessed at a mean 8 year follow-up. RESULTS: All the arthrodeses showed fusion at a mean 3.5 months (range: 2.5 to 6 months) postoperative delay without reintervention. Weight-bearing was resumed at 2 to 3 months. The external fixator was removed at a mean 5.2 months. No recurrence of infection was observed over a mean follow-up of 8.2 years (range: 1 to 15 years). Three complications occurred: one hematoma, managed surgically; one supracondylar fracture treated orthopedically; and one osteitis, managed by surgical curettage. DISCUSSION: This knee arthrodesis technique proved effective, with no failures in this short series, especially in cases of primary infection. It is a reproducible means of osteosynthesis, with little subsequent morbidity. Fixation in two orthogonal planes seemed to provide the stability required to achieve bone fusion. This assembly avoids internal fixation, which is never risk-free in a context of primary sepsis. LEVEL OF EVIDENCE: Level IV. Retrospective study.

[Coverage of chronic osteomyelitis of the ankle and the foot using a soleus muscle island flap, vascularized with retrograde flow on the posterior tibial artery. A seven cases report]. / Couverture des ostéites de cheville et du pied par un lambeau de muscle soléaire pédiculé en îlot rétrograde sur l'artère tibiale postérieure. A propos de sept cas.

AIM OF THE STUDY: The treatment of chronic osteomyelitis with large skin defects at the foot or the ankle is uneasy. In such cases, free muscular flaps are currently advised but they are less reliable in patients with medical diseases. In such difficult cases we have used the distally based soleus island flap, vascularized with retrograde flow on the posterior tibial artery. The technique and the indications of this flap are discussed. PATIENTS AND METHOD: This flap has been used for seven patients with bone infection and skin defects measuring an average of 10 x 7 cm. The preoperative arteriography had to find the whole three arteries at the leg, with a good distal anastomotic arcade. The soleus muscle was raised with the posterior tibial artery, after it was ligated proximally and dissected up to the tarsal tunnel. RESULTS: All of the seven flaps totally survived, except one that a marginal necrosis treated by excision and iterative dissection of the pedicle for a more distal repositioning. No clinical vascular deficiency was found on the legs. At the last review, all the osteomyelitis were cured. DISCUSSION: The soleus island flap, distally vascularized on the posterior tibial artery, is a reliable flap, useful for the coverage of the distal leg, from the ankle to the very distal foot. Harvesting a major artery at the leg should be weighed against the failure of a free flap in high risk patients.

Surgical excision of bone sarcomas involving the sacroiliac joint.

Adequate (wide or marginal and uncontaminated) margins and reconstruction are difficult to achieve when performing an internal hemipelvectomy for bone sarcomas involving the sacroiliac joint. We evaluated whether adequate surgical margins could be achieved and if functional outcomes could be predicted based on the type of resection and reconstruction. Forty patients had resections of the sacroiliac joint. Vertical sacral osteotomies were through the sacral wing (n = 2), ipsilateral sacral foramina (n = 27), sacral midline (n = 9), or contralateral foramina (n = 2). Iliac resections were Type I, Type I-II with partial or total acetabular re-section, or Type I-II-III. Surgical margins were adequate in 28 of 38 patients (74%), two (7%) of whom experienced local recurrence, compared with seven of 10 (70%) patients with inadequate margins. Reconstruction consisted of restoring continuity between the spine and pelvis. Resection of the entire acetabulum and removal of the lumbosacral trunk were the two main determinants of function, as assessed using the Musculoskeletal Tumor Society score. There were no life-threatening or function-threatening complications. Internal hemipelvectomy with a limb salvage procedure can be achieved with adequate surgical margins in selected patients. Functional outcomes can be predicted based on the type of resection and reconstruction, which helps the surgeon plan the procedure and inform the patient.

Influence of clinical outcome and outcome period definitions on estimates of absolute clinical and economic benefits of influenza vaccination in community dwelling elderly persons.

Studies assessing the clinical and economic benefits of vaccination in the elderly have used different clinical outcomes (e.g. hospitalizations for pneumonia or influenza versus hospitalizations for respiratory and cardiovascular causes) and different outcome periods (e.g. peak versus total influenza season) on which to base estimates of clinical effectiveness and cost effectiveness. We explored the implications of these varying approaches by comparing two health economic analysis models of influenza vaccination of community-dwelling elderly persons. We developed computerized models using clinical data from 3 large US HMOs for the 1998-1999 and 1999-2000 influenza seasons. The primary health economic model used a broad definition of clinical events and outcome period and included hospitalizations for all respiratory and cardiovascular events that occurred during the entire influenza season. The alternative model used more restrictive definitions and included pneumonia or influenza hospitalizations occurring during the peak influenza season. The results of Monte Carlo simulation showed that, with the more inclusive primary model, influenza vaccination resulted in net medical care cost savings due to fewer respiratory or cardiovascular hospitalizations of Dollars 71/person vaccinated (5th-95th percentile Dollars 32-118) and net savings of Dollars 809/year of life saved (5th-95th percentile Dollars 331-1450). In contrast, the alternate model found costs of Dollars 3.50/person vaccinated (5th-95th percentile Dollars -11 to 5) and net costs of Dollars 91/year of life saved (5th-95th percentile Dollars -309 to 126). Our findings confirm that influenza vaccination of the elderly is most likely cost saving and supports policies and programs that advocate routine immunization of all persons 65 and older. They also highlight how different outcome definitions can influence the results of health economic analyses.

Ambulatory-care diagnoses as potential indicators of outbreaks of gastrointestinal illness--Minnesota.

INTRODUCTION: Syndromic surveillance's capability to augment existing surveillance for community-acquired gastrointestinal disease is unknown. OBJECTIVE: The objective of this study was to evaluate the capability of a syndromic surveillance system to detect outbreaks of gastrointestinal disease. METHODS: A retrospective analysis was conducted comparing ambulatory care data from a health plan with a set of 110 gastrointestinal-disease outbreaks identified by the Minnesota Department of Health during 2001-02. Unusual clusters of illness (i.e., signals) in the health-plan data were identified by analyzing daily counts of gastrointestinal illness using an adjusted space-time scan statistic. Concordance was defined as < or =5 km between outbreak and signal and the signal occurring within 1 week of the outbreak. RESULTS: During 104 weeks, the number of signals was roughly what would have been expected by chance, suggesting that the modeling did a good job of estimating the expected counts of illness and that false alarms would not have occurred much more often than the number predicted at the various thresholds. During the same period, the health department identified 110 eligible gastrointestinal outbreaks. Apparent associations of the three statistically most unusual concordant signals with outbreaks of viral or bacterial gastrointestinal illness were ruled out by the health department on the basis of detailed knowledge of the circumstances and low numbers of affected persons seeking medical care. CONCLUSION: No previously known gastrointestinal outbreaks were identified by this surveillance system. However, relatively few recognized outbreaks resulted in patients seeking medical care, and the sensitivity of this system to detect outbreaks of real significance to public health remains to be determined. Prospective evaluation probably will be required to understand the usefulness of syndromic surveillance systems to enhance existing disease surveillance.

[Gait changes encountered after a total knee prosthesis with or without posterior cruciate ligament preservation]. / Modifications de la marche associées à la présence d'une prothèse totale de genou conservant ou sacrifiant le ligament croisé postérieur.

PURPOSE OF THE STUDY: We wanted to check whether the differences in joint kinematics between the normal and prosthesis knee, with or without preservation of the posterior cruciate ligament, have an effect on knee flexion-extension during gait and on gait performance. MATERIAL AND METHODS: A control group of nine subjects was compared with two groups of subjects with total knee prostheses, with (n = 10 patients) or without (n = 6 patients) preservation of the posterior cruciate ligament. Gait was studied on flat ground at three different walking speeds. We measured the principal temporospatial gait parameters as well as knee flexion and extension angles using continuous electrogoniometry. Non-parametric statistical tests were used to analyze data due to the small number of subjects in each group. RESULTS: The flexion-extension cycles were different between the control group and the prostheses groups, but there was no difference between the two prostheses groups. Measurements made during gait confirmed this result, demonstrating a modification of the temporospatial parameters and a decrease in knee flexion during weight bearing in the prostheses groups compared with the control group. The statistical analysis demonstrated a correlation between these two results. DISCUSSION: The individual nature of gait parameters hindered data analysis. Indeed, there are many different ways to walk "normally". We were however able to demonstrate the following points. The theoretical differences in joint kinematics between prostheses with or without preservation of the posterior cruciate ligament did not have any effect on gait. There were however significant differences between the control group and the prostheses groups, and these differences depended on walking speed. The most interesting results concerned the changes in the weight-bearing phase. Flexion during this phase was related to walking speed and was decreased in amplitude in both prostheses groups. This lesser amplitude in knee flexion probably affected the quality of gait because it was correlated with decreased temporospatial parameters related to gait performance. CONCLUSION: This decreased amplitude of flexion during gait, which cannot be expected from motion measurements without weight bearing, can be explained by an interaction between joint kinematics, the musculoligamentary system and the locomotor schema.

[Knee kinematics in flexion and extension using an electrogoniometric device: results in nine healthy subjects]. / Etude cinématique de la flexion-extension du genou à l'aide d'électrogoniomètre.

PURPOSE OF THE STUDY: We wanted to develop a gait evaluation protocol using an electrogoniometric device allowing simpler measurements than optoelectronic recordings. MATERIAL AND METHODS: Gait was studied in a group of nine healthy subjects, mean age 58 years, walking on flat ground at three different speeds. We recorded the knee flexion and extension angles and the main temporospatial gait parameters. The principal conditions required for considering gait to be normal were taken from the literature. RESULTS: The subjects exhibited gait cycles which were normal in 83% of the cases for both knees at all three walking speeds. In 17% of the cases, the subjects walked with a flexed knee or without flexion during the weight-bearing phase. Knee motion was symmetrical between the right and left knee in all subjects. Increased walking speed was associated with increases temporospatial parameters and greater flexion and extension angles, particularly during the weight-bearing phase. There was a correlation between the weight-bearing flexion phase and stride length. DISCUSSION: The walking distance was moderate but sufficient to avoid the influence of the start and stop cycles. The electrogoniometers were small and did not perturb walking. Certain temporospatial parameters could not be measured directly but could be estimated. We checked that the results corresponded with data in the literature. Lateralization (right, left dominance) did not influence knee movement. Flexion during weight-bearing could influence gait quality by affecting the balance between gravity and quadriceps muscle force, particularly when considering forces used to progress forward. Knee motion varies with walking speed and depends not only on overall knee motion measured without weight bearing, but probably also on the interaction between joint kinematics, the musculoligamentary system, and the locomotor schema.

[Mid-term results of Wallaby I posterior cruciate retaining total knee arthroplasty: a prospective study of the first 425 cases]. / Résultats à moyen terme de la prothèse totale du genou Wallaby I conservant le ligament croisé postérieur: à propos des 425 premiers cas suivis prospectivement.

PURPOSE OF THE STUDY: Posterior Wallaby I is a fixed polyethylene tibial plateau prosthesis enabling preservation of the posterior cruciate ligament (PCL). Its asymmetrical and divergent femoral condyles articulate with also asymmetrical tibial plateaus. The purpose of this prospective study was to analyze outcome of the first 425 Wallaby I prosthesis of the Guepar group implanted for first-intention treatment. MATERIALS AND METHODS: These 425 prostheses were implanted from December 1992 to February 1995 by senior and junior surgeons. Mean patient age at implantation was 70.5 years. 91% had primary or secondary osteoarthritis and only 8.9% had inflammatory rheumatoid disease. The mean preoperative IKS score was 25.34 points and the IKS function score was 29.04. 10.35% of knees were aligned normally (mechanical axis between 2 degrees varus and 3 degrees valgus) according to the IKS criteria (Ewald), 24% presented valgus > or = 4 degrees and 65.6% varus > or = 3 degrees. All tibial and patellar components (except one) were cemented, 5.8% of the femoral pieces were inserted without cement. All but 11 patellae were resurfaced. Clinical outcome was assessed with the IKS score and radiological outcome with the IKS criteria. The patella was considered to be tilted when the alpha angle was > 5 degrees and dislocated when the AA' distance was > 5 mm. The chi-square test was used for comparison of quantitative variables (significance set at 0.05). RESULTS: Early postoperative complications were rare: two infections cured with debridement-lavage and antibiotics without removal of the prosthesis, one peronal nerve palsy which regressed partially, ten late unions without clinical consequence (particularly in the inflammatory rheumatoid patients). Twenty-six prostheses were followed less than one year (eight patients died and eighteen were lost to follow-up) and 84 less than five years (27 patients died and 57 lost to follow-up before five years). 315 prostheses were followed for more than five years (5-9 years) with a mean follow-up of 6.3 years. Among the 399 prostheses followed for one year or more, we noted: four infections including three requiring change of the prosthesis (one cured by arthroscopic lavage), two aseptic loosenings which were revised (one global one tibial), one tibial loosening and three patellar loosenings which were not revised, and two femoral ossifications limiting joint motion but improved by arthrolysis and resection of the ossifications. Three patients experienced anterior pain requiring secondary patellar resurfacing in two and section of the lateral patellar wing in one. Ninteen patellar fractures (4.7%) were noted, including 17 with no significant functional impact which were not revised. The mean IKS knee score among prostheses followed for five years was 90.5 points, with mean motion 110.5 degrees. Mean IKS function score was 61.63 points. 72.9% of the knees were aligned, 22.2% in varus and 4.9% in valgus. The mechanical axis of 94.3% of the knees was between 5 degrees varus and 5 degrees valgus. Prosthesis survival at eight years (Kaplan-Meier method) was 97.7% considering all reasons for prosthesis removal and 98.5% for removal for aseptic loosening. CONCLUSION: This prospective multicentric study demonstrated that the results obtained with the Wallaby I prosthesis are as good as those obtained with other prostheses sparing the PCL and published in the literature. Preservation of the PCL enables better knee stability, correct motion (110.5 degrees in our series) with almost no radiological wear of the tibial polyethylene at eight years. The only worrisome complication is patellar fracture.

National Bioterrorism Syndromic Surveillance Demonstration Program.

The National Bioterrorism Syndromic Surveillance Demonstration Program identifies new cases of illness from electronic ambulatory patient records. Its goals are to use data from health plans and practice groups to detect localized outbreaks and to facilitate rapid public health follow-up. Data are extracted nightly on patient encounters occurring during the previous 24 hours. Visits or calls with diagnostic codes corresponding to syndromes of interest are counted; repeat encounters are excluded. Daily counts of syndromes by zip code are sent to a central data repository, where they are statistically analyzed for unusual clustering by using a model-adjusted SaTScan approach. The results and raw data are displayed on a restricted website. Patient-level information stays at the originating health-care organization unless required by public health authorities. If a cluster surpasses a threshold of statistical aberration chosen by the corresponding public health department, an electronic alert can be sent to that department. The health department might then call a clinical responder, who has electronic access to records of cases contributing to clusters. The system is flexible, allowing for changes in participating organizations, syndrome definitions, and alert thresholds. It is transparent to clinicians and has been accepted by the health-care organizations that provide the data. The system's data are usable by local and national health agencies. Its software is compatible with commonly used systems and software and is mostly open-source. Ongoing activities include evaluating the system's ability to detect naturally occurring outbreaks and simulated terrorism events, automating and testing alerts and response capability, and evaluating alternative data sources.