893 resultados para Variable sample size
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Data from the 2009–2011 School Physical Activity and Nutrition (SPAN) project were analyzed to examine the association between bullied status at school during the past six months and engaging in five or more days of physical activity during the past seven days in a population of 8th and 11th grade Texas youths after stratifying by gender. As a secondary aim, this study also examined the association between weight status and the prevalence of bullied status at school. The final sample size for this study, after excluding missing data, consisted of 6,246 8th and 11th grade youths (girls, n= 3,237; boys, n=3,009) representing a total of 518,838 youths from 8th and 11th grade. Results from the multiple logistic regression adjusting for weight status, grade, and ethnicity, indicate that girls with a bullied status of at least two or three times per month had significantly lower odds of engaging in five or more days of physical activity during the past seven days than girls who were never bullied at school (ORadj=0.62; 95% CI, 0.40, 0.96). Conversely, girls who reported a bullied status of at least once per week were significantly more likely to engage in five or more days of physical activity during the past seven days compared to girls who were never bullied at school (ORadj=3.44; 95% CI, 1.56, 7.63). No significant associations between bullied status and engaging in five or more days of physical activity during the past seven days were found for boys. Bullied status differed significantly across weight status for 8th grade girls (χ2(6)=63.7, p<.05) and 11th grade boys (χ2(6) =94.93, p<.05), with overweight and obese youths reporting a higher prevalence of being bullied once or twice, at least two or three times per month, and at least once per week than their normal weight peers. Our finding that girls with bullied status of at least once per week were more likely to engage in five or more days of physical activity than girls who were never bullied warrants future qualitative research to identify potential explanations for such results. Future research on relational and weight-based bullying is also needed and may help explain the inconsistent findings between bullied status and engaging in physical activity in girls.^
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Objective: The primary objective of this project was to describe the efficacy of the Levonorgestrel Intrauterine Device (LIUD) for treatment of Complex Endometrial Cancer (CAH) and Grade 1 Endometrial Cancer (G1EEC) in terms of rate of Complete Response (CR) and Partial Response (PR) after 6 months of therapy. Finally, we assessed if any clinical or pathologic features were associated with response to the LIUD. ^ Methods: This study was a retrospective case series designed to report the response rate of patients with CAH or G1EEC treated with LIUD therapy. In addition, this study has a laboratory component to assess molecular predictors of response to LIUD therapy. Retrospective data already collected from patients diagnosed with CAH or EEC grade 1 and treated with LIUD therapy at MD Anderson Cancer Center (MDACC) were used for this study. Patients from all ethnic and race groups were included. A Complete Response (CR) was defined in patients diagnosed with CAH if pathologic report at 6 months demonstrated either no evidence of hyperplasia or no atypia in the setting of simple or complex hyperplasia. Partial Response (PR) was recorded if disease downgraded to only CAH from G1EEC. No Response (NR) was recorded if pathologic report demonstrates no change (Stable Disease, SD) or progression to cancer (Progressive Disease, PD). We calculated the proportion of patients with complete response to LIUD therapy with 95% confidence interval. We compared the response rates (CR/PR vs NR) by obesity status (Obese if BMI > 40 kg/m2 vs non-obese if BMI <= 40 kg/m2) as well as other clinical and pathologic factors, such as age, uterine size (median size), and presence of exogenous progesterone effect. ^ Results: There were 39 patients diagnosed with either CAH or G1EEC treated with the LIUD. Of 39 patients, 12 did not have pathological results of biopsy at 6months time period. Of 27 evaluable patients, 17 were diagnosed with CAH and 10 with G1EEC. Overall response rate (RR) was 78% (95% CI = 62-94%) at 6 months, 18 patients had CR (4 in G1EEC; 14 in CAH), 3 patients had PR (3 in G1EEC), 3 had SD (1 in CAH; 2 in G1EEC), 3 had PD (2 in CAH; 1 in G1EEC). After histology stratification, RR at 6 months was 82.35% (14/17; 95%CI = 67.4-97.3%) in CAH and 70% (7/10; 95% CI = 41-98.4%) in G1EEC. ^ There was no difference in response (R) and no response (NR) based on BMI (p=0.56). He observed a trend showing association between age with response (p=0.1). There was no association between uterine size and response to therapy (p=0.17). We recorded strong association between exogenous progesterone effect and response. ^ Conclusion: LIUD therapy for the treatment of CAH and G1EEC may be effective and safe. Presence of exogenous progesterone effect may predict the response to LIUD therapy at earlier time points. There is need of further studies with larger sample size to explore the relationship of response with other clinical and pathologic factors^
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Aims: Obesity is a state of chronic inflammation characterized by depressed Th2 immune response. Animal studies have shown decreased IgA levels in obese rats and Leptin an adipose cell origin cytokine have been shown to enhance the activity of Clostridium difficile Toxin A. Hence we hypothesized that obesity is a risk factor for C. difficile infection (CDI) ^ Methods: 33 cases of CDI and 131 controls matched by age and HORNS index were identified from an IRB approved observational study at St. Luke's Episcopal Hospital in Houston. Variables like age, gender, height, weight, chronic antibiotic use, proton pump inhibitor use, diabetes mellitus, myocardial infarction, inflammatory bowel disease, diverticulitis, transfer from nursing home, hospital or home, nasogastric tube use and use of hemodialysis were provided in the dataset. Height and weight of the patient were used to calculate the BMI, based on which the study subjects were classified as obese and non-obese. Using STATA these variables were analyzed using test, chi square test followed by conditional logistic regression. ^ Results: On univariate analysis and conditional logistic regression, no significant increase in risk was associated with obesity (OR: 1.24; 95% CI: 0.46 - 3.36; p = 0.67) or BMI (OR: 0.98; CI: 0.92 - 1.04; p = 0.92). Hence, we cannot reject our hypothesis and conclude that "obesity is a risk factor associated with higher incidence of CDI in hospitalized patients. On univariate analysis using hemodialysis, nursing home transfer, home transfer, PPI and chronic antibiotics were found to be significantly different (p<0.05) in the cases and controls. On conditional logistic regression home (OR: 3.4; 95% CI: 1.15 - 9.61) and hemodialysis (OR: 4.1; 95% CI: 1.14 - 15.57) were found to be significantly different (p<0.05) between the case and control groups. ^ Conclusion: Our results show that obesity is not a significant risk factor for CDI. Our sample size was small and hence this may need conformation with a larger study. Patients transferred from home to the hospital and patients on hemodialysis had significantly higher incidence of CDI.^
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There is not a large body of evidence on in-utero exposure to chemotherapy for pregnancy-associated cancers to help determine the long term effects on offspring. This study is a systematic review of long term follow-up to find evidence for adverse outcomes in exposed offspring. In order for studies to be eligible for this systematic review, they had to have a median follow up of at least 24 months with the resulting child. PubMed, Medline, and Scopus were the databases used, and we included all eligible articles, regardless of the date of publication. The search resulted in six articles meeting the eligibility requirements. The review of findings of these studies suggested that there is not enough evidence to make a determination of the risk of chemotherapy for the offspring. Exposed children in the sample of reviewed papers did have some medical conditions, but the rate and type did not differ from the non-exposed population. However, a limitation of this literature review is the very small sample size of publications on this important topic. This finding of few studies on this topic is an important result of this systematic review. More research and long term follow-up studies must be conducted to address this issue.^
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Background: Cancer is the second-leading cause of death in the United States, and Asian Americans/Pacific Islanders are the only racial/ethnic group for which cancer is the leading cause of death. Regular cancer screenings help to identify precancerous lesions and cancer at an earlier stage, when the cancer is more treatable. Ethnic disparities in participation in cancer screenings are also striking, and evidence indicates that Asian Americans may have lower rates of cancer screening participation than other racial/ethnic groups. The Health of Houston Survey 2010 (HHS 2010) is an address-based survey, administered via telephone, website, and mail, of over 5,000 respondents in Houston and Harris County that provides recent data on the health status and needs of the Houston community. HHS 2010 researchers oversampled for Asians and Vietnamese Americans in order to obtain a sample size large enough to obtain statistical power. This dataset provides a unique opportunity to examine the cancer screening behaviors and predictors of Vietnamese and Chinese Americans living in Houston, Texas.^ Methods: This study was a secondary data analysis of HHS 2010 data. The data were analyzed to compare the breast, cervical, and colorectal cancer screening compliance rates of Vietnamese and Chinese Americans with other racial/ethnic groups in Houston, Texas. Key predictors of participation and barriers to cancer screening were identified.^ Results: The results of this study indicate that in Houston, Vietnamese Americans and Asian Americans as a whole have strikingly lower rates of participation in cancer screenings compared to other ethnic groups. Chinese Americans had the highest rate of noncompliance for mammography of all ethnic groups; Asian Americans and Vietnamese Americans also had high rates of noncompliance. Similarly, Vietnamese and Asian Americans had high rates of noncompliance with colorectal cancer screening recommendations. Importantly, Vietnamese, Chinese, and Asian Americans had by far the worst pap test participation, with noncompliance rates more than double that of all other racial/ethnic groups. In general, the findings indicated several key predictors in cancer screening behaviors, including English language proficiency, years lived in the United States, health insurance, college education, and income; however, the significance and patterns of these variables varied by ethnic group as well as cancer site.^ Conclusions: This secondary analysis highlights the disparities in cancer screening participation among Vietnamese, Chinese, and Asian Americans in Houston, Texas and indicate the need to identify Asian Americans as a high-risk group in need of health promotion attention. Barriers to screening and educational needs appear to be specific to each target ethnic group. Thus, health educators and health professionals in Houston must focus on the specific educational needs of the key ethnic groups that make up the Houston population. Further, more ethnic-specific research is needed to examine the health behaviors and needs of Houston's Asian American subgroups.^
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Head and Neck Squamous Cell Carcinoma (HNSCC) is the sixth common malignancy in the world, with high rates of developing second primary malignancy (SPM) and moderately low survival rates. This disease has become an enormous challenge in the cancer research and treatments. For HNSCC patients, a highly significant cause of post-treatment mortality and morbidity is the development of SPM. Hence, assessment of predicting the risk for the development of SPM would be very helpful for patients, clinicians and policy makers to estimate the survival of patients with HNSCC. In this study, we built a prognostic model to predict the risk of developing SPM in patients with newly diagnosed HNSCC. The dataset used in this research was obtained from The University of Texas MD Anderson Cancer Center. For the first aim, we used stepwise logistic regression to identify the prognostic factors for the development of SPM. Our final model contained cancer site and overall cancer stage as our risk factors for SPM. The Hosmer-Lemeshow test (p-value= 0.15>0.05) showed the final prognostic model fit the data well. The area under the ROC curve was 0.72 that suggested the discrimination ability of our model was acceptable. The internal validation confirmed the prognostic model was a good fit and the final prognostic model would not over optimistically predict the risk of SPM. This model needs external validation by using large data sample size before it can be generalized to predict SPM risk for other HNSCC patients. For the second aim, we utilized a multistate survival analysis approach to estimate the probability of death for HNSCC patients taking into consideration of the possibility of SPM. Patients without SPM were associated with longer survival. These findings suggest that the development of SPM could be a predictor of survival rates among the patients with HNSCC.^
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Background: interventions that focus on improving eating habits, increasing physical activity, and reducing sedentary behaviors on weight status and body mass index percentile and z-scores in youths have not been well documented. This study aimed to determine the short and long term effects of a 2-week residential weight management summer camp program for youths on weight, BMI, BMI percentile, and BMI z-score. ^ Methods: A sample of 73 obese multiethnic 10-14 years old youths (11.9 ± 1.4) attended a weight management camp called Kamp K'aana for two weeks and completed a 12-month follow-up on height and weight. As part of Kamp K'aana, participants received a series of nutrition, physical activity and behavioral lessons and were on an 1800 kcal per day meal plan. Anthropometric measurements of height and weight were taken to calculate participants' BMI percentiles and z-scores. Paired t-tests, chi square test and ANCOVA, adjusting for age, gender, and ethnicity were used to assess changes in body weight, BMI, BMI percentiles and BMI z-scores pre to two-weeks post-camp and 12 months post-camp. ^ Results: Significant reductions in body weight of 3.6 ± 1.4 (P = 0.0000), BMI of 1.4 ± 0.54 (P = 0.0000), BMI percentile of 0.45 ± 0.06 (P = 0.0000), and BMI z-score of 0.1 ± 0.06 (P = 0.0000) were observed at the end of the camp. Significant reductions in BMI z-scores (P < 0.001) and BMI percentile (P < 0.001) were observed at the 12-month reunion when compared to pre- and two-weeks post camp data. There was a significant increase in weight and BMI (P = 0.0000) at the 12-month reunion when compared to pre and post camp measurements. ^ Conclusion: Kamp K'aana has consistently shown short-term reductions in weight, BMI, BMI percentile, and BMI z-score. Results from analysis of long-term data suggest that this intervention had beneficial effects on body composition in an ethnically diverse population of obese children. Further research which includes a control group, larger sample size, and cost-analysis should be conducted.^
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Background: For most cytotoxic and biologic anti-cancer agents, the response rate of the drug is commonly assumed to be non-decreasing with an increasing dose. However, an increasing dose does not always result in an appreciable increase in the response rate. This may especially be true at high doses for a biologic agent. Therefore, in a phase II trial the investigators may be interested in testing the anti-tumor activity of a drug at more than one (often two) doses, instead of only at the maximum tolerated dose (MTD). This way, when the lower dose appears equally effective, this dose can be recommended for further confirmatory testing in a phase III trial under potential long-term toxicity and cost considerations. A common approach to designing such a phase II trial has been to use an independent (e.g., Simon's two-stage) design at each dose ignoring the prior knowledge about the ordering of the response probabilities at the different doses. However, failure to account for this ordering constraint in estimating the response probabilities may result in an inefficient design. In this dissertation, we developed extensions of Simon's optimal and minimax two-stage designs, including both frequentist and Bayesian methods, for two doses that assume ordered response rates between doses. ^ Methods: Optimal and minimax two-stage designs are proposed for phase II clinical trials in settings where the true response rates at two dose levels are ordered. We borrow strength between doses using isotonic regression and control the joint and/or marginal error probabilities. Bayesian two-stage designs are also proposed under a stochastic ordering constraint. ^ Results: Compared to Simon's designs, when controlling the power and type I error at the same levels, the proposed frequentist and Bayesian designs reduce the maximum and expected sample sizes. Most of the proposed designs also increase the probability of early termination when the true response rates are poor. ^ Conclusion: Proposed frequentist and Bayesian designs are superior to Simon's designs in terms of operating characteristics (expected sample size and probability of early termination, when the response rates are poor) Thus, the proposed designs lead to more cost-efficient and ethical trials, and may consequently improve and expedite the drug discovery process. The proposed designs may be extended to designs of multiple group trials and drug combination trials.^
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Adolescents 15 – 19 years of age have the highest prevalence of Chlamydia trachomatis out of any age group, reaching 28.3% among detained youth [1]. The 2010 Center for Disease Control guidelines recommend one dose of azithromycin for the treatment of uncomplicated chlamydia infections based on 97% cure rate with azithromycin. Recent studies found an 8% or higher failure rate of azithromycin treatment in adolescents [2-5]. We conducted a prospective study beginning May, 2012 in the Harris County Juvenile Justice Center (HCJJC) medical department. Study subjects were detainees with positive urine NAAT tests for chlamydia on intake. We provided treatment with Azithromycin, completed questionnaires assessing risk factors and performed a test of cure for chlamydia three weeks after successful treatment. Those with treatment failure (positive TOC) received doxycycline for seven days. The preliminary results summarized herein are based on data collected from May 2012 to January 2013. Of the 97 youth enrolled in the study to date, 4 (4.1%) experienced treatment failure after administration of Azithromycin. Of these four patients, all were male, African-American and asymptomatic at the time of initial diagnosis and treatment. Of note, 37 (38%) patients in the cohort complained of abdominal pain with administration of Azithromycin. Results to date suggest that the efficacy of Azithromycin in our study is higher than the recent reported studies indicating a possible upper bound of Azithromycin. These results are preliminary and recruitment will continue until a sample size of 127 youth is reached.^
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OBJECTIVE: To systematically review published literature to examine the complications associated with the use of misoprostol and compare these complications to those associated with other forms of abortion induction. ^ DATA SOURCES: Studies were identified through searches of medical literature databases including Medline (Ovid), PubMed (NLM), LILACS, sciELO, and AIM (AFRO), and review of references of relevant articles. ^ STUDY SELECTION AND METHODS: A descriptive systematic review that included studies reported in English and published before December 2012. Eligibility criteria included: misoprostol (with or without other methods) and any other method of abortion in a developing country, as well as quantitative data on the complication of each method. The following is information extracted from each study: author/year, country/city, study design/study sample, age range, setting of data collection, sample size, the method of abortion induction, the number of cases for each method, and the percentage of complications with each method. RESULTS: A total of 4 studies were identified (all in Latin America) describing post-abortion complications of misoprostol and other methods in countries where abortion is generally considered unsafe and/or illegal. The four studies reported on a range of complications including: bleeding, infection, incomplete abortion, intense pelvic pain, uterine perforation, headache, diarrhea, nausea, mechanical lesions, and systemic collapse. The most prevalent complications of misoprostol-induced abortion reported were: bleeding (7-82%), incomplete abortion (33-70%), and infection (0.8-67%). The prevalence of these complications reported from other abortion methods include: bleeding (16-25%), incomplete abortion (15-82%), and infection (13-50%). ^ CONCLUSION: The literature identified by this systematic review is inadequate for determining the complications of misoprostol used in unsafe settings. Abortion is considered an illicit behavior in these countries, therefore making it difficult to investigate the details needed to conduct a study on abortion complications. Given the differences between the reviewed studies as well as a variety of study limitations, it is not possible to draw firm conclusions about the rates of specific-abortion related complications.^
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The problem of analyzing data with updated measurements in the time-dependent proportional hazards model arises frequently in practice. One available option is to reduce the number of intervals (or updated measurements) to be included in the Cox regression model. We empirically investigated the bias of the estimator of the time-dependent covariate while varying the effect of failure rate, sample size, true values of the parameters and the number of intervals. We also evaluated how often a time-dependent covariate needs to be collected and assessed the effect of sample size and failure rate on the power of testing a time-dependent effect.^ A time-dependent proportional hazards model with two binary covariates was considered. The time axis was partitioned into k intervals. The baseline hazard was assumed to be 1 so that the failure times were exponentially distributed in the ith interval. A type II censoring model was adopted to characterize the failure rate. The factors of interest were sample size (500, 1000), type II censoring with failure rates of 0.05, 0.10, and 0.20, and three values for each of the non-time-dependent and time-dependent covariates (1/4,1/2,3/4).^ The mean of the bias of the estimator of the coefficient of the time-dependent covariate decreased as sample size and number of intervals increased whereas the mean of the bias increased as failure rate and true values of the covariates increased. The mean of the bias of the estimator of the coefficient was smallest when all of the updated measurements were used in the model compared with two models that used selected measurements of the time-dependent covariate. For the model that included all the measurements, the coverage rates of the estimator of the coefficient of the time-dependent covariate was in most cases 90% or more except when the failure rate was high (0.20). The power associated with testing a time-dependent effect was highest when all of the measurements of the time-dependent covariate were used. An example from the Systolic Hypertension in the Elderly Program Cooperative Research Group is presented. ^
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The introduction of new medical treatments in recent years, commonly referred to as highly active antiretroviral therapy, has greatly increased the survival of patients with HIV/AIDS. As patients with HIV/AIDS continue to live longer, other important health-related outcomes, such as quality of life (QOL), should be thoroughly studied. There is also evidence that racial/ethnic minorities are disproportionately affected by HIV/AIDS, but potential health disparities among individuals already infected with HIV/AIDS have not been adequately examined in ethnically diverse populations. The purpose of this dissertation was to: (1) examine the impact of both demographic and behavioral variables on functional status and overall QOL among a population of ethnically diverse and economically disadvantaged HIV/AIDS patients; (2) examine the psychometric properties of a functional status measure—the Household and Leisure Time Activities questionnaire (HLTA); and (3) assess a proximal-distal theoretical framework for QOL using a full structural equation model in a population of patients with HIV/AIDS. Analyses were performed using data collected in the fall of 2000 from the project, Health and Work-Related Quality of Life and Health Risk Behaviors in a Multiethnic HIV-positive Population . Investigators from The University of Texas M.D. Anderson Cancer Center, The University of Texas-Houston Medical School, and The University of Texas School of Public Health conducted this project. The study site was the Thomas Street Clinic (TSC), a comprehensive HIV/AIDS care facility funded by the Harris County Hospital District (HCHD). TSC provides HIV/AIDS care to a diverse population of approximately 4000 medically indigent residents of Harris County. A systematic, consecutive sampling procedure yielded a sample size of 348 patients. Findings suggested that overall QOL, work-role functioning, household functioning, and leisure time functioning were impaired in this patient population. Results from the psychometric evaluation indicated that the HLTA was a reliable and valid measure of household and leisure time functioning status in a low-income multiethnic HIV-positive population. Finally, structural equation modeling of the proximal-distal QOL model suggested that this model was not a viable representation of the relationship between the study variables in this patient population. ^
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La capacidad de la red de canales en un sistema de riego depende de satisfacer la demanda hídrica máxima de los cultivos. Los métodos para determinar la capacidad del canal requieren de la estimación de la variable agronómica: evapotranspiración de los cultivos. En grandes áreas de riego, con un padrón diversificado de cultivos, diferentes fechas de siembra y varios ciclos agrícolas no existe un procedimiento integrado para estimar esta variable agronómica, lo cual genera incertidumbre al ser requerida en los métodos. En este trabajo se desarrolla una propuesta para estimar dicha variable para grandes zonas de riego. La propuesta inicia con el cálculo de la evapotranspiración de los cultivos por fecha de siembra, y termina con la obtención de una curva general integral para un año agrícola, encontrándose la variable evapotranspiración de una zona de riego (ETzr). Esta metodología se aplicó para el canal principal del módulo de riego Santa Rosa, Distrito de Riego 075, Sinaloa, México en que la ETzr resultó de 4,1 mm d-1. Por los resultados se concluye la veracidad de la propuesta en determinar la evapotranspiración para el cálculo en la capacidad del canal.
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We present a reconstruction of El Niño Southern Oscillation (ENSO) variability spanning the Medieval Climate Anomaly (MCA, A.D. 800-1300) and the Little Ice Age (LIA, A.D. 1500-1850). Changes in ENSO are estimated by comparing the spread and symmetry of d18O values of individual specimens of the thermocline-dwelling planktonic foraminifer Pulleniatina obliquiloculata extracted from discrete time horizons of a sediment core collected in the Sulawesi Sea, at the edge of the western tropical Pacific warm pool. The spread of individual d18O values is interpreted to be a measure of the strength of both phases of ENSO while the symmetry of the d18O distributions is used to evaluate the relative strength/frequency of El Niño and La Niña events. In contrast to previous studies, we use robust and resistant statistics to quantify the spread and symmetry of the d18O distributions; an approach motivated by the relatively small sample size and the presence of outliers. Furthermore, we use a pseudo-proxy approach to investigate the effects of the different paleo-environmental factors on the statistics of the d18O distributions, which could bias the paleo-ENSO reconstruction. We find no systematic difference in the magnitude/strength of ENSO during the Northern Hemisphere MCA or LIA. However, our results suggest that ENSO during the MCA was skewed toward stronger/more frequent La Niña than El Niño, an observation consistent with the medieval megadroughts documented from sites in western North America.
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Twenty-one narwhals tagged in 2003 and 2004 in Admiralty Inlet showed a different summer distributional pattern than previous narwhal-tracking studies from Somerset Island, Eclipse Sound and Melville Bay. The migration of the narwhals tracked from Admiralty Inlet moved out through Lancaster Sound 15 days earlier (P <0.0001) than the narwhals summering around Eclipse Sound, whereas the Admiralty Inlet narwhals reached the mouths of Eclipse Sound 18 days later (P <0.0001) than the Eclipse Sound summering population. The winter range of the Admiralty Inlet narwhals overlapped with the winter range of narwhals from Melville Bay and Eclipse Sound in central southern Baffin Bay and Northern Davis Strait, but not with the winter range of narwhals from Somerset Island that wintered further north. Distribution size of range, and population size did not appear to be related. An example of considerable year to year variation between area of summer and winter distribution in the 2 years was believed to be related to the sample size and number of pods of whales tagged, rather than to differences in sex or age classes.