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author:("lisat, mehran")
1.  State by State Variation in Emergency versus Elective Colon Resections: Room for Improvement 
Compared to elective surgical procedures, emergency procedures are associated with higher cost, morbidity, and mortality. This study seeks to investigate potential state-by-state variations in the incidence of emergent versus elective colon resections.
A retrospective analysis of all adult patients (≥18years) included in the Nationwide Inpatient Sample from 2005–2009 who underwent hemicolectomy (right or left) or sigmoidectomy was conducted. Discharge-level weights were applied and generalized linear models were used to assess the odds of a patient undergoing emergent versus elective colon surgery nationally and for each state after adjusting for patient and hospital factors. Odds ratios were estimated with the national average as the reference.
The final study cohort included 203,050 observations comprised of 83,090 emergent and 119,960 elective colectomies. The state with the highest unadjusted proportion of emergent procedures was Nevada (53.6%), while Texas had the lowest (2.8%). Compared to the national average, the adjusted odds of undergoing emergency colectomy remained highest in Nevada (OR: 1.70; 95% CI: 1.54–1.87) and lowest in Texas (OR: 0.43; 95% CI: 0.36–0.51)..
Substantial state variations exist in rates of emergency colon surgery within the United States. Identification of these differences suggests significant variations in practice and a potential to decrease the number of emergent colon operations.
Level of Evidence
Level III Prognostic and Epidemiological Study
PMCID: PMC3645918  PMID: 23609280
Emergency Colon Surgery; State Variation; Outcomes
2.  Disparities in mortality after blunt injury: Does insurance type matter? 
The Journal of surgical research  2012;177(2):288-294.
Insurance-related outcomes disparities are well-known, but associations between distinct insurance types and trauma outcomes remain unclear. Prior studies have generally merged various insurance types into broad groups. The purpose of this study is to determine the association of specific insurance types with mortality after blunt injury.
Materials and Methods
Cases of blunt injury among adults aged 18-64 years with an Injury Severity Score (ISS)>9 were identified using the 2007-2009 National Trauma Data Bank. Crude mortality was calculated for ten insurance types. Multivariable logistic regression was employed to determine difference in odds of death between insurance types, controlling for ISS, Glasgow Coma Scale motor, mechanism of injury, sex, race and hypotension. Clustering was used to account for possible inter-facility variations.
312,312 cases met inclusion criteria. Crude mortality ranged from 3.2-6.0% by insurance type. Private Insurance, Blue Cross Blue Shield, Workers Compensation, and Medicaid yielded the lowest relative odds of death, while Not Billed and Self Pay yielded the highest. Compared to Private Insurance, odds of death were higher for No Fault (OR 1.25, p=0.022), Not Billed (OR 1.77, p<0.001), and Self Pay (OR 1.78, p<0.001). Odds of death were higher for Medicare (OR 1.52, p<0.001) and Other Government (OR 1.35, p=0.049), while odds of death were lower for Medicaid (OR 0.89, p=0.015).
Significant differences in mortality after blunt injury were seen between insurance types, even among those commonly grouped in other studies. Policymakers may use this information to implement programs to monitor and reduce insurance-related disparities.
PMCID: PMC3989534  PMID: 22858381
Insurance type; Blunt injury; Disparities; Outcomes
3.  Predictors of Sepsis in Moderately Severely Injured Patients: An Analysis of the National Trauma Data Bank 
Surgical Infections  2013;14(1):62-68.
Post-traumatic sepsis is a significant cause of in-hospital death. However, socio-demographic and clinical characteristics that may predict sepsis in injured patients are not well known. The objective of this study was to identify risk factors that may be associated with post-traumatic sepsis.
Retrospective analysis of patients in the National Trauma Data Bank for 2007–2008. Patients older than 16 years of age with an Injury Severity Score (ISS) ≥9 points were included. Multivariable logistic regression was used to determine association of sepsis with patient (age, gender, ethnicity, and insurance status), injury (mechanism, ISS, injury type, hypotension), and clinical (major surgical procedure, intensive care unit admission) characteristics.
Of a total of 1.3 million patients, 373,370 met the study criteria, and 1.4% developed sepsis, with an associated mortality rate of approximately 20%. Age, male gender, African-American race, hypotension on emergency department presentation, and motor vehicle crash as the injury mechanism were independently associated with post-traumatic sepsis.
Socio-demographic and injury factors, such as age, race, hypotension on admission, and severity and mechanism of injury predict post-traumatic sepsis significantly. Further exploration to explain why these patient groups are at increased risk is warranted in order to understand better and potentially prevent this life-threatening complication.
PMCID: PMC3601717  PMID: 23461696
4.  Predictors of Positive Head CT Scan and Neurosurgical Procedures After Minor Head Trauma 
The Journal of surgical research  2011;173(1):31-37.
There continues to be an ongoing debate regarding the utility of Head CT scans in patients with a normal Glasgow Coma Scale (GCS) after minor head injury. The objective of this study is to determine patient and injury characteristics that predict a positive head CT scan or need for a Neurosurgical Procedure (NSP) among patients with blunt head injury and a normal GCS.
Materials and Methods
Retrospective analysis of adult patients in the National Trauma Data Bank who presented to the ED with a history of blunt head injury and a normal GCS of 15. The primary outcomes were a positive head CT scan or a NSP. Multivariate logistic regression controlling for patient and injury characteristics was used to determine predictors of each outcome.
Out of a total of 83,566 patients, 24,414 (29.2%) had a positive head CT scan and 3,476 (4.2%) underwent a NSP. Older patients and patients with a history of fall (as compared to a motor vehicle crash) were more likely to have a positive finding on a head CT scan. Male patients, African-Americans (as compared to Caucasians) and those who presented with a fall were more likely to have a NSP.
Older age, male gender, ethnicity and mechanism of injury are significant predictors of a positive finding on head CT scans and the need for neurosurgical procedures. This study highlights patient and injury specific characteristics that may help in identifying patients with supposedly minor head injury who will benefit from a head CT scan.
PMCID: PMC3684145  PMID: 21872271
Head Injury; Outcomes; Ethnicity; Gender; Age; Disparities; Multivariate Regression; Blunt Trauma
5.  Influence of the National Trauma Data Bank on the Study of Trauma Outcomes: Is it Time to Set Research Best Practices to Further Enhance Its Impact? 
Risk-adjusted analyses are critical in evaluating trauma outcomes. The National Trauma Data Bank (NTDB) is a statistically robust registry that allows such analyses; however, analytical techniques are not yet standardized. In this study, we examine peer-reviewed manuscripts published using NTDB data, with particular attention to characteristics strongly associated with trauma outcomes. Our objective is to determine if there are substantial variations in the methodology and quality of risk-adjusted analyses and thus, whether the development of best practices for risk-adjusted analyses is warranted.
Study Design
A database of all studies utilizing NTDB data published through December 2010 was created by searching Pubmed and Embase. Studies with multivariate risk-adjusted analyses were examined for their central question, main outcome measures, analytical techniques, the co-variates in adjusted analyses, and handling of missing data.
Of 286 NTDB publications, 122 performed a multivariable adjusted analysis. These studies focused on Clinical Outcomes (51), Public Health Policy or Injury Prevention (30), Quality (16), Disparities (15), Trauma Center Designation (6) or Scoring Systems (4). Mortality was the main outcome in 98 of these studies. There were considerable differences in the co-variates used for case adjustment. The three most frequently controlled for co-variates were age (95%), Injury Severity Score (85%) and gender (78%). Up to 43% of studies did not control for the five basic covariates necessary to conduct a risk-adjusted analysis of trauma mortality. Less than 10% of studies used clustering to adjust for facility differences or imputation to handle missing data.
There is significant variability in how risk-adjusted analyses using data from the NTDB are performed. Best practices are needed to further improve the quality of research from the NTDB.
PMCID: PMC3334459  PMID: 22321521
National Trauma Data Bank; NTDB; Outcomes; Policy; Quality; Covariates; Disparities; Trauma Center
6.  Demographic and Clinical Features of Dengue Fever in Pakistan from 2003–2007: A Retrospective Cross-Sectional Study 
PLoS ONE  2010;5(9):e12505.
Demographic features of dengue fever have changed tremendously in Pakistan over the past two decades. Small scale studies from all over the country have reported different aspects of individual outbreaks during this time. However, there is scarcity of data looking at the overall trend of dengue virus infection in the country. In this study, we examined annual trends, seasonality, and clinical features of dengue fever in the Pakistani population.
Demographic information and dengue IgM status of all patients tested for dengue IgM antibody at Aga Khan University Hospital from January 2003 to December 2007 were analyzed to look for trends of IgM-positive cases in Pakistan. In addition, clinical and biochemical parameters were abstracted retrospectively from medical records of all patients hospitalized with IgM-proven dengue fever between January 2006 and December 2007. These patients were categorized into dengue fever and dengue hemorrhagic fever according to the WHO severity grading scale.
Out of a total of 15040 patients (63.2% male and 36.8% female), 3952 (26.3%) tested positive for dengue IgM antibody. 209 IgM proven dengue patients were hospitalized during the study period. During 2003, IgM positive cases were seen only during the months of July-December. In contrast, such cases were detected throughout the year from the 2004–2007. The median age of IgM positive patients decreased every year from 32.0 years in 2003 to 24.0 years in 2007 (p<0.001). Among hospitalized patients, nausea was the most common presenting feature found in 124/209 (59.3%) patients. Children presented with a higher median body temperature than adults (p = 0.010). In addition, neutropenia was seen more commonly in children while raised serum ALT levels were seen more commonly in adults (both p = 0.006). While a low total white cell count was more common in patients with dengue fever as compared to Dengue Hemorrhagic Fever (p = 0.020), neutropenia (p = 0.019), monocytosis (p = 0.001) and raised serum ALT level (p = 0.005) were observed more commonly in the latter group.
Dengue virus is now endemic in Pakistan, circulating throughout the year with a peak incidence in the post monsoon period. Median age of dengue patients has decreased and younger patients may be more susceptible. Total and differential leukocyte counts may help identify patients at risk of hemorrhage.
PMCID: PMC2938342  PMID: 20856935
Brain research  2008;1214:35-39.
The secondary afferents of the olfactory system largely project to the ipsilateral cortex without synapsing in the thalamus, making unilateral olfactory testing a useful probe of ipsilateral hemispheric activity. In light of evidence that lateralized performance on some perceptual tasks may be influenced by estrogen, we assessed left:right nostril differences in two measures of olfactory function in 14 post-menopausal women receiving estrogen replacement therapy (ERT) and 48 post-menopausal women receiving no such therapy. Relative to women not taking ERT, those receiving ERT exhibited better performance in the left nostril and poorer performance in the right nostril on an odor memory/discrimination test. Similar laterality effects were not observed for an odor detection threshold test employing phenyl ethyl alcohol. These results suggest that estrogen influences the lateralization of an odor memory/discrimination task and that hormone replacement therapy in the menopause may be an excellent paradigm for understanding lateralizing effects of hormones on some sensory processes.
PMCID: PMC2481562  PMID: 18466883
laterality; odor memory; odor discrimination; estrogen; hormone replacement therapy
8.  Classification and Clinical Features of Headache Disorders in Pakistan: A Retrospective Review of Clinical Data 
PLoS ONE  2009;4(6):e5827.
Morbidity associated with primary headache disorders is a major public health problem with an overall prevalence of 46%. Tension-type headache and migraine are the two most prevalent causes. However, headache has not been sufficiently studied as a cause of morbidity in the developing world. Literature on prevalence and classification of these disorders in South Asia is scarce. The aim of this study is to describe the classification and clinical features of headache patients who seek medical advice in Pakistan.
Methods and Results
Medical records of 255 consecutive patients who presented to a headache clinic at a tertiary care hospital were reviewed. Demographic details, onset and lifetime duration of illness, pattern of headache, associated features and family history were recorded. International Classification of Headache Disorders version 2 was applied.
66% of all patients were women and 81% of them were between 16 and 49 years of age. Migraine was the most common disorder (206 patients) followed by tension-type headache (58 patients), medication-overuse headache (6 patients) and cluster headache (4 patients). Chronic daily headache was seen in 99 patients. Patients with tension-type headache suffered from more frequent episodes of headache than patients with migraine (p<0.001). Duration of each headache episode was higher in women with menstrually related migraine (p = 0.015). Median age at presentation and at onset was lower in patients with migraine who reported a first-degree family history of the disease (p = 0.003 and p<0.001 respectively).
Patients who seek medical advice for headache in Pakistan are usually in their most productive ages. Migraine and tension-type headache are the most common clinical presentations of headache. Onset of migraine is earlier in patients with first-degree family history. Menstrually related migraine affects women with headache episodes of longer duration than other patients and it warrants special therapeutic consideration. Follow-up studies to describe epidemiology and burden of headache in Pakistan are needed.
PMCID: PMC2688080  PMID: 19503794

Results 1-8 (8)