Estimating tuberculosis cases and their economic costs averted in the United States over the past two decades.

BACKGROUND: Following a concerted public health response to the resurgence of tuberculosis (TB) in the United States in the late 1980s, annual TB incidence decreased substantially. However, no estimates exist of the number and cost savings of TB cases averted. METHODS: TB cases averted in the United States during 1995-2014 were estimated: Scenario 1 used a static 1992 case rate; Scenario 2 applied the 1992 rate to foreign-born cases, and a pre-resurgence 5.1% annual decline to US-born cases; and a statistical model assessed human immunodeficiency virus and TB program indices. We applied the cost of illness to estimate the societal benefits (costs averted) in 2014 dollars. RESULTS: During 1992-2014, 368 184 incident TB cases were reported, and cases decreased by two thirds during that period. In the scenarios and statistical model, TB cases averted during 1995-2014 ranged from approximately 145 000 to 319 000. The societal benefits of averted TB cases ranged from US$3.1 to US$6.7 billion, excluding deaths, and from US$6.7 to US$14.5 billion, including deaths. CONCLUSIONS: Coordinated efforts in TB control and prevention in the United States yielded a remarkable number of TB cases averted and societal economic benefits. We illustrate the value of concerted action and targeted public health funding.

Modelling tuberculosis trends in the USA.

We present a mathematical transmission model of tuberculosis in the USA. The model is calibrated to recent trends of declining incidence in the US-born and foreign-born populations and is used in assessing relative impacts of treatment of latently infected individuals on elimination time, where elimination is defined as annual incidence <1 case/million. Provided current control efforts are maintained, elimination in the US-born population can be achieved before the end of this century. However, elimination in the foreign-born population is unlikely in this timeframe even with higher rates of targeted testing and treatment of residents of and immigrants to the USA with latent tuberculosis infection. Cutting transmission of disease as an interim step would shorten the time to elimination in the US-born population but foreign-born rates would remain above the elimination target.

Quality control of smear microscopy for acid-fast bacilli: the case for blinded re-reading.

SETTING: Quality control of sputum smear microscopy, which is essential for ensuring correct tuberculosis (TB) diagnosis, is often performed through the unblinded rereading of all positive slides and a sample of negative slides. OBJECTIVE: To assess misclassification error introduced by knowledge of prior results. METHODS: The Southern Vietnam Regional TB Laboratory prepared three gold-standard sets of 750 slides: an unblinded set, an unblinded set in which 13% of negative slides were replaced by weakly positive slides purposefully mislabelled as negative, and a blinded set. Six provincial technicians who normally perform district quality control each reread 125 slides from each set. RESULTS: In the three sets only one negative slide was misread as positive. In the unblinded set (referent), 2.9% (9/311) positive slides were misread as negative, compared with 18.7% (57/305) in the blinded set (prevalence ratio [PR] = 6.5; 95% confidence interval [CI] 3.3-12.8; P < 0.001), and 11.3% (33/293) in the unblinded set with mislabelled slides (PR = 3.9; 95%CI 1.9-8.0; P < 0.001). CONCLUSIONS: False-negative error was more common than false-positive error. Knowledge of prior reading influences re-reading. Blinded re-reading of systematically selected slides would appear preferable, although this method requires high levels of proficiency among quality control technicians.

Low birthweight and infant mortality in Puerto Rico.

OBJECTIVES: The purpose of this study was to quantify the relative contributions of maternal age, education, marital status, hospital of birth, and use of prenatal care to the high incidence of low birthweight and infant mortality in Puerto Rico. METHODS: An analysis was conducted of 257,537 live births that occurred from 1986 through 1989 among Puerto Rico residents and the 3373 corresponding infant deaths. Binomial multiple regression models were used to calculate the adjusted population attributable risks for each variable. RESULTS: Our estimates indicate that approximately 6 of every 10 infant deaths on the island are potentially preventable if low birthweight were eradicated, regardless of other associated factors. Eliminating risks associated with sociodemographic and socioeconomic factors (including hospital of birth) would potentially decrease the incidence of low birth-weight in Puerto Rico by one third. Specifically, the elimination of risks associated with the socioeconomic disadvantage of women delivering in public hospitals alone would potentially decrease Puerto Rico's low birthweight incidence by 28%, regardless of other factors considered in our study. CONCLUSIONS: Efforts to prevent low birthweight and infant mortality in Puerto Rico should focus on reducing the gap between the private and public sectors.

Impact of very low birthweight on the black-white infant mortality gap.

In recent years, the rate of decline for the black infant mortality risk (IMR) has been slower than that for whites. The resultant widening in the black-white infant mortality gap has been accompanied by an increased percentage of very low birthweight (VLBW) infants (227 g-1,499 g) among black live births. Restricting our analysis to non-Hispanic black and white single live births, we used the 1983 national linked birth-death file to assess the relative contribution of VLBW infants to the black-white gap in IMR. VLBW occurred among 2.3% of all black live births and among 0.8% of all white live births. Deaths among VLBW infants accounted for 62.5% of the black-white gap in IMR. Although VLBW newborns represent a fraction of all live births in the United States, they account for almost two-thirds of the black-white gap in IMR. Since preterm delivery is associated with most VLBW infant deaths, our findings indicate the crucial need to identify strategies that reduce preterm births, among blacks in particular, to reduce significantly the infant mortality gap in the United States.

Morbidity estimates of conditions originating in the perinatal period: United States, 1986 through 1987.

Morbidity estimates of conditions originating in the perinatal period have not been reported in the United States. Conditions originating in the perinatal period were identified according to the International Classification of Diseases. The National Hospital Discharge Survey provided a weighted, nationally representative sample of newborns discharged each year from short-stay, nonfederal hospitals. From 1986 through 1987, 33.7% of all newborns had at least one nonteratologic perinatal condition. However, 6.8% of all newborns had physiologic jaundice as their only discharge diagnosis. Nonphysiologic jaundice was diagnosed in 4.4%, maternal causes of perinatal morbidity in 3.1%, birth trauma in 2.5%, fetal distress in 2.3%, birth asphyxia in 2.1%, and infections specific to the perinatal period in 2.0% of all newborn discharges. The average hospital stay for all newborns was 3.5 days, but it was 5.3 days for newborns with at least one nonteratologic perinatal condition and 2.6 for newborns discharged without a morbid condition. This study provides nationally representative estimates of perinatal morbidity useful for comparisons with smaller hospital-based samples. In addition, the study provides estimates of the public health impact of these conditions in terms of hospital stay days.

Infant mortality among Hispanics. A portrait of heterogeneity.

In the United States, infant mortality risks among Hispanics have not been previously evaluated at the national level. We used the 1983 and 1984 national Linked Birth and Infant Death data sets to compare infant mortality risks among single-delivery infants of Hispanic descent with those among single-delivery infants of non-Hispanic whites (the reference group). We also included the 1983 and 1984 linked birth cohort for single-delivery infants in Puerto Rico. Among all Hispanic groups, the neonatal (less than 28 days) mortality risk was higher among Puerto Rican islanders (relative risk [RR] = 2.3) and continental Puerto Ricans (RR = 1.5) and lower among Cuban-Americans (RR = 1.0) and Mexican-Americans (RR = 1.0). The postneonatal mortality risk (28 to 364 days) was highest among continental Puerto Ricans (RR = 1.2) and lowest among Cuban-Americans (RR = 0.6). Our study underscores the heterogeneity of the Hispanic population in the United States and suggests that interventions to prevent infant mortality be tailored to ethnic-specific risk factors and outcomes.

Breastfeeding patterns in Puerto Rico.

In the 1950s, Puerto Rico began an active industrialization program. We used data from the 1982 Puerto Rico Fertility and Family Planning Assessment to describe the trend in the incidence of breastfeeding in Puerto Rico over time and to ascertain some of its determinants. From 1946 through 1982, 5,884 infants were born among this statistically representative sample of reproductive-aged women. The proportion of infants who had ever been breastfed was 59 percent for births before 1960 (mean duration = 7.8 months), dropped to 25 percent for infants born from 1970 to 1974 (mean duration = 4.9), and rose to 38 percent for births delivered from 1980 to 1982 (mean duration = 3.4). Prior breastfeeding experience was an important determinant of breastfeeding a newborn. Infants of mothers who had breastfed a previous baby were 7.3 times more likely to be breastfed (95% confidence interval = 6.6, 8.0) compared with infants of mothers who had not previously breastfed. The 38 percent of infants who were breastfed in Puerto Rico in the early 1980s is below the 74 percent to 97 percent reported in Latin America and below the 54 percent reported in the United States for the same period. This study provides baseline data for any future intervention strategies.

Diabetes mellitus during pregnancy and the risks for specific birth defects: a population-based case-control study.

Although the excess risk for birth defects among children of mothers with diabetes mellitus is well documented, there are few data concerning the risk for specific malformations. In the Atlanta Birth Defects Case-Control Study, those risks for malformations were evaluated. The population-based study included 4929 live and stillborn babies with major malformations ascertained by the Metropolitan Atlanta Congenital Defects Program in the first year of life born to residents of Metropolitan Atlanta between 1968 and 1980. The study also included 3029 nonmalformed live babies who were frequency-matched to case babies by race, period of birth, and hospital of birth. The relative risk for major malformations among infants of mothers with insulin-dependent diabetes mellitus (n = 28) was 7.9 (95% confidence interval [CI]1.9, 33.5) compared with infants of nondiabetic mothers. The relative risks for major central nervous system and cardiovascular system defects were 15.5 (95% CI = 3.3, 73.8) and 18.0 (95% CI = 3.9, 82.5), respectively. The absolute risks for major, central nervous system, and cardiovascular system malformations among infants of diabetic mothers were 18.4, 5.3, and 8.5 per 100 live births, respectively. Infants of mothers with gestational diabetes mellitus who required insulin during the third trimester of pregnancy were 20.6 (95% CI = 2.5, 168.5) times more likely to have major cardiovascular system defects than infants of nondiabetic mothers. The absolute risk for infants of this group of diabetic mothers was 9.7%. No statistically significant differences were found among infants of mothers with gestational diabetes mellitus who did not require insulin during pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of a regionalized perinatal care system through linked infant birth and death certificates: Puerto Rico 1980-84.

The birth weight-specific neonatal mortality rates for Puerto Rico are among the highest rates reported in the United States. Furthermore, since 1979, Puerto Rico's neonatal mortality rate has been higher than the neonatal mortality rate for blacks in the United States. Since the proportion of births less than 2,500 grams has remained relatively unchanged in the past 10-15 years in Puerto Rico and in the continental United States, those findings suggest problems of either access or quality of the neonatal care in Puerto Rico. Therefore, we used linked infant birth-death certificates from 1980 through 1984 to evaluate the regionalization of perinatal health services operating on the island. We found that 41.6% of all births less than 1,500 grams were delivered at hospitals without Neonatal Intensive Care Units (NICUs). In addition, delivery at hospitals with NICUs did not confer a survival advantage for infants less than 2,500 grams. The lack of survival advantage in most hospitals with NICUs persisted after we adjusted simultaneously for birth weight, Apgar score at 5 minutes, and history of pregnancy complications. We conclude that the regionalization plan operating on the island needs reevaluation and recommend that preventive measures at the primary, secondary, and tertiary levels be implemented.

Maternal thyroid disease and risk of birth defects in offspring: a population-based case-control study.

We investigated the relationship between maternal thyroid disease and the risk of birth defects in offspring using data from a large population-based, case-control study. Cases included 4904 stillborn and liveborn infants with major anomalies diagnosed in the first year of life and born to residents of metropolitan Atlanta between 1968 and 1980. Controls included 3027 normal babies, frequency-matched to cases by race, hospital of birth and quarter of birth. We compared mothers of cases and controls regarding history of physician-diagnosed hypothyroidism and hyperthyroidism before the infant's birth, age at diagnosis of thyroid condition, duration of illness, and intake of thyroid medications before and during pregnancy. Information obtained from maternal interviews was evaluated for concordance with hospital records. We adjusted for potentially confounding factors using conditional logistic regression analysis. Overall, there was no relationship between the risk of total birth defects and history of maternal hypothyroidism (odds ratio (OR) = 1.05, 95% C.I. 0.84-1.31), maternal hyperthyroidism (OR = 1.00, 95% C.I. 0.66-1.53), and intake of thyroid hormone and antithyroid drugs before and during pregnancy. In an analysis of 66 specific birth defects and defect groups, we found two statistically significant associations with hypothyroidism and three with hyperthyroidism which may reflect chance findings. In an evaluation of babies with multiple anomalies, we observed a two-fold increased risk with hypothyroidism but no discernible pattern of defects. The absolute risk of major birth defects in offspring of women with history of hypothyroidism can be estimated as 2.1%, a finding at odds with the 10-20% risk cited in the literature.

Clinical-epidemiologic assessment of pattern of birth defects associated with human teratogens: application to diabetic embryopathy.

The concepts of sensitivity, specificity, and predictive value can be used to assess patterns of birth defects associated with human teratogens. Although sensitivity of any single defect is generally low for many known teratogens, the presence of specific defect combinations is usually predictive of the teratogen. To evaluate the patterns of birth defects associated with diabetic embryopathy, a sensitivity-specificity analysis was performed on 4929 infants with major defects ascertained by the population-based Metropolitan Atlanta Congenital Defects Program between 1968 and 1980. By reviewing hospital records, maternal insulin-dependent diabetes mellitus was confirmed in 26 infants. Patterns of defects were evaluated among infants born to mothers with insulin-dependent diabetes mellitus and compared with the rest of the Metropolitan Atlanta Congenital Defects Program case population. Multiple logistic regression analysis was used to assess defect combinations that predict for insulin-dependent diabetes mellitus. Of 26 infants, 8 had multiple defects. However, most defects and their combinations were poorly sensitive and predictive for insulin-dependent diabetes mellitus. The predictive value for insulin-dependent diabetes mellitus was greatest for the combination of vertebral and cardiovascular anomalies (6.5%). Also, several pathogenetic mechanisms were noted among patients with insulin-dependent diabetes mellitus, such as cell migration defects, cell death events, deformations, and cardiac flow lesions. The inability to find a clear-cut phenotype for diabetic embryopathy may be due to several etiologic factors and mechanisms associated with diabetic embryopathy.

Evaluation of a regionalized perinatal care system through linked infant birth and death certificates: Puerto Rico, 1980-84.

The birth weight-specific neonatal mortality rates for Puerto Rico are among the highest rates reported in the United States. Furthermore, since 1979, Puerto Rico's neonatal mortality rate has been higher than the neonatal mortality rate for blacks in the United States. Since the proportion of births less than 2,500 grams has remained relatively unchanged in the past 10-15 years in Puerto Rico and in the continental United States, those findings suggest problems of either access or quality of the neonatal care in Puerto Rico. Therefore, we used linked infant birth-death certificates from 1980 through 1984 to evaluate the regionalization of perinatal health services operating on the island. We found that 41.6% of all births less than 1,500 grams were delivered at hospitals without Neonatal Intensive Care Units (NICUs). In addition, delivery at hospitals with NICUs did not confer a survival advantage for infants less than 2,500 grams. The lack of survival advantage in most hospitals with NICUs persisted after we adjusted simultaneously for birth weight, Apgar score at 5 minutes, and history of pregnancy complications. We conclude that the regionalization plan operating on the island needs reevaluation and recommend that preventive measures at the primary, secondary, and tertiary levels be implemented.

Maternal smoking and low birthweight in the reproductive history of women in Puerto Rico, 1982.

In 1982, a representative sample of 3,175 women ages 15 to 49 years living in Puerto Rico were interviewed and complete reproductive histories obtained. Births to mothers who started smoking regularly at some time before delivery and who were still smoking at the time of the interview (the exposure definition) were compared with unexposed births. Our analysis of 4,444 single, live births delivered in public and private hospitals from 1946 through 1982 demonstrates that births to smoking women aged 20 and older delivering in public hospitals were 2.5 times more likely to weigh less than 2,500 grams (95% confidence interval (CI) = 1.9, 2.3), and on the average weighed 207 grams less (95% CI = 130, 284) than births to a comparable group of nonsmoking mothers. However, we found no other difference in birthweight between newborns of smoking and nonsmoking women when comparing their births within the same hospital category and age group. The data in this study suggest that the effect of smoking on birthweight among births to Puerto Rican women may be modified by maternal age and by whether the infant was born in a private or public hospital.