T C Smith

Naval Health Research Center, San Diego, California, United States

Are you T C Smith?

Claim your profile

Publications (17)57.72 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background:Although overweight and obesity are less prevalent among active-duty military personnel compared with similar persons not serving in the military, no such differences have been observed between veterans and non-veterans.Objectives:To assess the magnitude of weight changes before, concurrent with and following discharge from the military, relative to weight during service, and to determine the demographic, service-related and psychological characteristics associated with clinically important weight gain among those who were discharged from military service during follow-up.Methods:Eligible Millennium Cohort Study participants (n=38 686) completed the questionnaires approximately every 3 years (2001, 2004 and 2007) that were used to estimate annual weight changes, as well as the percentage experiencing clinically important weight gain, defined as 10%. Analyses were stratified by sex.Results:Weight gain was greatest around the time of discharge from service and in the 3 years before discharge (1.0-1.3 kg per year), while it was nearly half as much during service (0.6-0.7 kg per year) and 3 years after service ended (0.7 kg per year). Consequently, 6-year weight gain was over 2 kg greater in those who were discharged compared with those who remained in the military during follow-up (5.7 vs 3.5 kg in men; 6.3 vs 4.0 kg in women). In those who were discharged, younger age, less education, being overweight at baseline, being in the active-duty component (vs Reserve/National Guard) and having experienced deployment with combat exposures (vs non-deployment) were associated with increased risks of clinically important weight gain.Conclusions:This study provides the first prospectively collected evidence for an increased rate of weight gain around the time of military discharge that may explain previously reported higher rates of obesity in veterans, and identifies characteristics of higher-risk groups. Discharge from military service presents a window of risk and opportunity to prevent unhealthy weight gain in military personnel and veterans.International Journal of Obesity advance online publication, 10 April 2012; doi:10.1038/ijo.2012.46.
    International journal of obesity (2005) 04/2012; 37(2). DOI:10.1038/ijo.2012.46 · 5.39 Impact Factor
  • Annals of Epidemiology 09/2010; 20(9):720-721. DOI:10.1016/j.annepidem.2010.07.086 · 2.15 Impact Factor
  • Annals of Epidemiology 09/2010; 20(9):722-722. DOI:10.1016/j.annepidem.2010.07.089 · 2.15 Impact Factor
  • Annals of Epidemiology 09/2009; 19(9):669. DOI:10.1016/j.annepidem.2009.07.029 · 2.15 Impact Factor
  • Annals of Epidemiology 09/2009; 19(9):651–652. DOI:10.1016/j.annepidem.2009.07.087 · 2.15 Impact Factor
  • Annals of Epidemiology 09/2008; 18(9):721-722. DOI:10.1016/j.annepidem.2008.08.047 · 2.15 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: There has been considerable publicity that the 1991 Gulf War may have caused a wide array of health problems in military personnel. Although postwar health outcomes have been studied in US, British, Canadian, and other deployed troops, this issue has not been previously evaluated in coalition forces native to the Gulf region. A collaborative team of US and Saudi health researchers was assembled, data sources evaluated, and hospitalizations among Saudi Arabian National Guard (SANG) soldiers between 1991 and 1999 analyzed. Multivariate modeling was used to evaluate differences between 8342 soldiers exposed to combat at Al Khafji and a comparison group of 7270 soldiers in the Riyadh area. This is the first reported epidemiological investigation of postwar hospitalization among coalition forces native to the Gulf region that participated in the 1991 Gulf War. A very small increase in hospitalizations was identified in SANG soldiers exposed to combat at Al Khafji. However, because of data limitations, the clinical relevance of this finding should be interpreted with caution. Future collaborative studies to better understand the health effects of deployment should be encouraged.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Viral hepatitis remains a health threat for military forces. Most recently, there has been concern about hepatitis C virus transmission during military service because a high prevalence of hepatitis C virus infection has been found in some U.S. veteran populations. In this study, hospitalizations of active duty U.S. military personnel for hepatitis were evaluated using standardized computer records. Only the first hospitalization was assessed during the period January 1, 1989, to December 31, 1999. Among active duty forces, the rate of hospitalization for all types of acute hepatitis declined from 13 to 1.1 per 100,000 personnel from 1989 to 1999. Males, nonwhite racial/ethnic groups, and older troops were more likely to be hospitalized for acute hepatitis. This study's finding of declining rates of acute hepatitis is a continuation of a trend observed since 1974. The decreasing risk of viral hepatitis in the U.S. military is attributable to several factors, including reduced levels of injection drug use because of routine, randomized drug testing.
    Military medicine 11/2001; 166(10):862-5. · 0.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Military Special Forces trainees undergo intense psychological and physical stressors that often lead to respiratory infection. During 1998-2000, 477 Navy Special Forces trainees were enrolled in a double-blind trial of oral azithromycin (1 g given weekly) plus a placebo injection, compared with benzathine penicillin G (1.2 million U) plus azithromycin placebo tablets. Among the 464 subjects with complete data, 44 developed acute respiratory infection (20 with pneumonia) during the 2 weeks of most intense training; of these subjects, 12 (27.3%) had evidence of Chlamydia pneumoniae infection and 7 (15.9%) had evidence of Mycoplasma pneumoniae infection. Trainees who received azithromycin were less likely than were trainees who received benzathine penicillin G to develop acute respiratory infection (risk ratio, 0.50; 95% confidence interval [CI], 0.28-0.92) and less likely at the end of training to report episodes of breathing difficulty (odds ratio [OR], 0.59; 95% CI, 0.34-1.01) or sore throat (OR, 0.66; 95% CI, 0.41-1.05). Compared with benzathine penicillin G prophylaxis, weekly oral azithromycin was superior in preventing respiratory infection in this population at transient high risk.
    Clinical Infectious Diseases 11/2001; 33(7):983-9. DOI:10.1086/322626 · 9.42 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To provide surveillance among US military personnel and their beneficiaries, 157 invasive Streptococcus pneumoniae clinical isolates were collected systematically from 7 large military hospitals between August 1997 and August 1999. The isolates were studied for antibiotic resistance, and 120 were serotyped and subjected to arbitrarily primed polymerase chain reaction (AP-PCR). Fifty (31.9%) of 157 isolates had intermediate or high-level resistance to penicillin, and 15.9% had multidrug resistance. The most common serotypes were 4, 6B, 9V, 14, 19F, and 23F. Those serotypes associated with penicillin resistance were 6B, 9V, 19A, and 19F. Most invasive disease cases were caused by serotypes included in the currently available 23- and 7-valent pneumococcal vaccines. By use of AP-PCR, 4 DNA groups were correlated with health care site (P< or =.0001). These results are valuable in assessing appropriate use of antibiotics and vaccines against S. pneumoniae in both military personnel and their families.
    The Journal of Infectious Diseases 10/2001; 184(5):591-6. DOI:10.1086/322786 · 5.78 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this effort was to assist the Nevada State Health Department in identifying cases of lymphoid or myeloid leukemia during the cluster period, from 1 January 1997 to the present, in Navy and Marine Corps personnel or their dependents under age 25, using existing electronic data resources. The Nevada State Health Department identified a cluster of 12 cases of acute lymphocytic leukemia (ALL) that were diagnosed in children and teenagers in Churchill County, Nevada, a rural county approximately 50 miles east of Reno, Nevada. There is a permanent complement at NSAWC/NAS Fallon of approximately 1,038 Naval officers and enlisted personnel, and fewer than 10 Marine Corps personnel. One of the 12 Churchill County cases was diagnosed in a child of an active-duty Navy enlisted person. For this reason, the Nevada State Epidemiologist asked the Navy for help in locating other possible leukemia cases in children of Naval personnel who may have left Churchill County and would be unknown to the Nevada State Health Department. At the request of BUMED and the Commanding Officer, NAS/NSAWC Fallon, the Naval Health Research Center (NHRC) joined the effort to assist the Nevada State Health Department on 16 March 2001 in case finding. This project was partially supported under work unit no.60126, part of a special Congressional allocation managed by the Department of Defense for Cancer Studies supporting the Hollings Cancer Center of the Medical University of South Carolina.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Since the Vietnam War, concern regarding the association of military exposures and birth defects has grown. The possibility of such associations remains a source of unease. To determine if such an association exists, birth defects surveillance among military families must be conducted. This project compared health record abstraction (active surveillance) with screening of Department of Defense electronic medical data (passive surveillance) to detect birth defects among San Diego County military families during the period January 1, 1997, through June 30, 1998. A total of 171 of 5,351 infants (3.2%) were identified as having a major defect, consistent with national civilian rates. There was approximately 80% concurrence between passive and active surveillance birth defect data, suggesting that a hybrid system of electronic data, supplemented with active surveillance in a specific region, represents a feasible and cost-effective surveillance program for the geographically dispersed military population.
    Military medicine 03/2001; 166(2):179-83. · 0.77 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Active duty US Naval mobile construction battalion personnel (Seabees) were surveyed in 1994 for the presence of a variety of symptoms. Questions were drawn from the Hopkins Symptom Checklist and from a collection of symptoms either defining clinical depression or commonly reported by Persian Gulf War veterans. Of those surveyed, 524 were Gulf War veterans and 935 were nondeployed Gulf War-era veterans. Factor analysis applied to Gulf War veterans yielded five factors, three deriving from the Hopkins Symptom Checklist, one suggesting clinical depression, and one containing symptoms commonly reported by Gulf War veterans. Factor analysis applied to nondeployed veterans yielded five similar factors. Three of the factors yielded statistically significantly greater standardized factor scores for Gulf War veterans than for nondeployed veterans. Four of the factors resembled factors resulting from a previous analysis on a sample of similar Gulf War veterans. Gulf War veterans and nondeployed era veterans reported similar clusters of symptoms and illnesses. However, Gulf War veterans reported these same clusters with greater frequencies than did nondeployed veterans. The authors conclude that, in contrast to a previous report, factor analysis did not identify a unique Gulf War syndrome.
    American Journal of Epidemiology 09/2000; 152(4):379-88. DOI:10.1093/aje/152.4.379 · 4.98 Impact Factor
  • Source
    Tyler C. Smith, Gregory C. Gray, James D. Knoke
    [Show abstract] [Hide abstract]
    ABSTRACT: Since the Persian Gulf War ended in 1991, veterans have reported diverse, unexplained symptoms. Some have wondered if their development of systemic lupus erythematosus, amyotrophic lateral sclerosis, or fibromyalgia might be related to Gulf War service. The authors used Cox proportional hazard modeling to determine whether regular, active-duty service personnel deployed to the Persian Gulf War (n = 551,841) were at increased risk of postwar hospitalization with the three conditions compared with nondeployed Gulf War era service personnel (n = 1,478,704). All hospitalizations in Department of Defense facilities from October 1, 1988, through July 31, 1997, were examined. With removal of personnel diagnosed with any of the three diseases before August 1, 1991, and adjustment for multiple covariates, Gulf War veterans were not at increased risk of postwar hospitalization due to systemic lupus erythematosus (risk ratio (RR) = 0.94, 95% confidence interval (CI): 0.65, 1.35). Because of the small number of cases and wide confidence limits, the data regarding amyotrophic lateral sclerosis were inconclusive. Gulf War veterans were slightly at risk of postwar hospitalization for fibromyalgia (RR = 1.23, 95% Cl: 1.05, 1.43); however, this risk difference was probably due to the Gulf War veteran clinical evaluation program beginning in 1994. These data do not support Gulf War service and disease associations.
    American Journal of Epidemiology 07/2000; 151(11):1053-9. DOI:10.1093/oxfordjournals.aje.a010147 · 4.98 Impact Factor
  • Source
    G C Gray, T C Smith, H K Kang, J D Knoke
    [Show abstract] [Hide abstract]
    ABSTRACT: A previous epidemiologic study demonstrated no unexplained increase in risk for postwar hospitalization among Gulf War veterans who had remained on active duty. The authors sought to expand this study to include Reserve and separated military personnel. They examined hospitalization data from the Department of Defense, the Department of Veterans Affairs (VA), and the California Office of Statewide Health Planning and Development hospital systems for the years 1991-1994. Since denominator data were not available, the authors compared the proportional morbidity ratios (PMRs) of hospitalization discharge diagnoses (both large categories and specific diagnoses) between Gulf War veterans and other veterans of the same era. There were no indications that Gulf War veterans were suffering increased PMRs for infectious diseases; neoplasms; endocrine diseases; blood diseases; skin conditions; or diseases of the nervous system, circulatory system, or musculoskeletal system. However, these veterans did experience proportionally more hospitalizations for various specific diagnoses, namely, fractures and bone and soft-tissue injuries (Department of Defense and California Office of Statewide Health Planning and Development), various diseases of the respiratory (including asthma) and digestive systems (VA), and diverse symptom diagnoses (VA). While these findings may be influenced by chance or by a number of potential confounders, including health registry participation, they merit further examination using other study designs.
    American Journal of Epidemiology 02/2000; 151(1):63-71. DOI:10.1093/oxfordjournals.aje.a010123 · 4.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Using Department of Defense hospital data, the authors examined the postwar hospitalization experience from March 1991 through September 1995 of US Gulf War veterans who were near Khamisiyah, Iraq, during nerve agent munition destruction in March 1991. Multiple sources of meteorologic, munition, and toxicology data were used to circumscribe geographic areas of low level, vaporized nerve agent for 4 days after the destruction. Plume estimates were overlaid on military unit positions, and exposure was estimated for the 349,291 US Army Gulf War veterans. Exposure was classified as not exposed (n = 224,804), uncertain low dose exposure (n = 75,717), and specific estimated subclinical exposure (n = 48,770) categorized into three groups for dose-response evaluation. Using Cox proportional hazard modeling, the authors compared the postwar experiences of these exposure groups for hospitalization due to any cause, for diagnoses in 15 unique categories, and for specific diagnoses an expert panel proposed as most likely to reflect latent disease from such subclinical exposure. There was little evidence that veterans possibly exposed to the nerve agent plumes experienced unusual postwar morbidity. While there were several differences in hospitalization risk, none of the models suggested a dose-response relation or neurologic sequelae. These data, having a number of limitations, do not support the hypothesis that Gulf War veterans are suffering postwar morbidity from subclinical nerve agent exposure.
    American Journal of Epidemiology 10/1999; 150(5):532-40. DOI:10.1093/oxfordjournals.aje.a010043 · 4.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Since the Persian Gulf War ended in 1991, many veterans have sought medical evaluation in the Department of Veterans Affairs Persian Gulf Veterans' Health Registry (VA registry) or the Department of Defense's Comprehensive Clinical Evaluation Program (DoD registry). Using combined data collected from 1993 to 1997 from the VA and DoD registries, the authors compared the characteristics of registry participants (n=74,653) with those of all Gulf War veterans (n=696,531) to determine the personnel most likely to seek medical evaluation. Using multiple logistic regression, the authors found that service branch and type were strongly associated with registry participation, with Army (adjusted odds ratio (OR)=4.7, 95% confidence interval (CI) 4.6-4.9) and National Guard (OR=2.6, 95% CI 2.5-2.6) personnel at highest odds compared with reference category personnel. Registry participants also were more likely to have been stationed in the Gulf War theater during the fighting (OR=2.2), to be older (>31 years/<22 years OR=2.1), to have been an enlisted person (OR=2.0), to have been construction workers (OR=1.3), to be female (OR=1.3), and to have been hospitalized during the 12-month period before the war (OR=1.2). These findings are useful in generating hypotheses regarding postwar morbidity. They also suggest that subpopulations of Gulf War veterans have a higher prevalence of symptoms and merit further study.
    American Journal of Epidemiology 08/1998; 148(4):343-9. DOI:10.1093/oxfordjournals.aje.a009651 · 4.98 Impact Factor