Do changes in primary care service use over time differ by neighbourhood income? Population-based longitudinal study in British Columbia, Canada.

BACKGROUND: Strong primary care systems have been associated with improved health equity. Primary care system reforms in Canada may have had equity implications, but these have not been evaluated. We sought to determine if changes in primary care service use between 1999/2000 and 2017/2018 differ by neighbourhood income in British Columbia. METHODS: We used linked administrative databases to track annual primary care visits, continuity of care, emergency department (ED) visits, specialist referrals, and prescriptions dispensed over time. We use generalized estimating equations to examine differences in the magnitude of change by neighbourhood income quintile, adjusting for age, sex/gender, and comorbidity, and stratified by urban/rural location of residence. We also compared the characteristics of physicians providing care to people living in low- and high-income neighbourhoods at two points in time. RESULTS: Between 1999/2000 and 2017/8 the average number of primary care visits per person, specialist referrals, and continuity of care fell in both urban and rural settings, while ED visits and prescriptions dispensed increased. Over this period in urban settings, primary care visits, continuity, and specialist referrals fell more rapidly in low vs. high income neighbourhoods (relative change in primary care visits: Incidence Rate Ratio (IRR) 0.881, 95% CI: 0.872, 0.890; continuity: partial regression coefficient -0.92, 95% CI: -1.18, -0.66; specialist referrals: IRR 0.711, 95%CI: 0.696, 0.726), while ED visits increased more rapidly (IRR 1.06, 95% CI: 1.03, 1.09). The percentage of physicians who provide the majority of visits to patients in neighbourhoods in the lower two income quintiles declined from 30.6% to 26.3%. CONCLUSION: Results raise concerns that equity in access to primary care has deteriorated in BC. Reforms to primary care that fail to attend to the multidimensional needs of low-income communities may entrench existing inequities. Policies that tailor patterns of funding and allocation of resources in accordance with population needs, and that align accountability measures with equity objectives are needed as part of further reform efforts.

Reasons for testing and exposure sources among women of childbearing age with moderate blood lead levels.

The purpose of this study was to examine the circumstances under which women receive blood lead tests in New York State and to characterize the sources of lead exposure among women of childbearing age with moderate blood lead levels. Telephone interviews were conducted with 135 women between the ages of 18 and 45, with blood lead levels from 10 through 25 micrograms/dl, were used to collect information on the reason for their blood lead test and possible sources of lead exposure. It was found that the two most common reasons to be tested for blood lead were workplace screening (47%) and pregnancy (27%). Occupational exposure was the primary source of lead exposure in this population (46%). Another common source of lead exposure was home renovation (24%). A significant proportion (31%) of women with blood lead levels from 10 through 25 micrograms/dl had no known current source of lead exposure. Based on New York's sample, there are a significant number of women of reproductive age with potentially fetotoxic blood lead levels.

Effects of maternal work activity during pregnancy on infant malformations.

This article examines the association between two birth defects, neural tube defects and oral cleft defects, and maternal physical work demands during the periconceptional period. A case-control study was conducted by comparing exposure characteristics of mothers of malformed infants, as ascertained from the New York State Congenital Malformations Registry (n = 520), with mothers of non-malformed infants (n = 1154). Case groups were further subdivided on whether infants had additional defects. Occupational exposure information was collected from a self-administered questionnaire, and demographic variables from vital records. The results showed no general differences between cases and controls in most variables. However, those infants with cleft defects plus additional defects tended to have a marginally increased risk (odds ratio = 1.76; 95% confidence interval, 1.02-3.21) in relation to maternal jobs requiring standing (> or = 75% of time). We suggest that exposure assessment be improved and defects subdivided for future studies.

Does paternal occupational lead exposure increase the risks of low birth weight or prematurity?

The relation between paternal occupational lead exposure and low birth weight/prematurity was examined in a retrospective cohort study. Birth weight and gestational age (1981-1992), obtained from New York State birth certificates, were compared between lead-exposed and nonexposed workers. The exposed group (n = 4,256) consisted of births to male workers of reproductive age reported to the New York State Heavy Metals Registry. The control group (n = 2,318) consisted of the offspring of a random sample of male bus drivers, frequency matched by age and residence. There were no statistically significant differences in birth weight or gestational age between the exposed and the control groups. However, workers who had elevated blood lead levels for more than 5 years had a higher risk of fathering a child with low birth weight (risk ratio = 3.85, 95% confidence interval 1.5-9.88) or prematurity (risk ratio = 2.45, 95% confidence interval 1.03-5.84) than did controls after adjustment for paternal age, low maternal education, race, residence, gravidity, maternal spontaneous abortion history, perinatal complications, adequacy of prenatal care, and infant gender. The risks of low birth weight and prematurity increased with the duration of exposure to lead. Our results were limited by the inability to control for some potential confounders, such as pregravid underweight and maternal nutrition status.

Environmental pollution and child health in central and Eastern Europe.

For the last 50 years, the economic and industrial development of the nations of Central and Eastern Europe has been achieved at the cost of environmental degradation. The health risks posed by this pollution to children and the steps necessary to ameliorate such risks are only beginning to be investigated. At a recent conference in Poland, sponsored in part by the National Institute of Environmental Health Sciences, participants from 11 countries in the region, together with scientists from Western Europe and the United States, met to share information regarding pediatric environmental health in Central and Eastern Europe, to consider methodologic issues in the design and conduct of such studies, and to discuss preventive strategies. This report summarizes the deliberations, outlines problem areas such as heavy metals and air pollution, delineates research and training needs to help Central and Eastern Europeans deal more effectively with such problems, and recommends specific future actions and collaborative efforts.

Maternal residential exposure to hazardous wastes and risk of central nervous system and musculoskeletal birth defects.

The authors used a case-control design to evaluate the risk of central nervous system and musculoskeletal birth defects relative to exposure to solvents, metal, and pesticide contaminants from hazardous waste sites. Cases included 473 central-nervous-system-defect births and 3305 musculoskeletal-defect births to residents of 18 counties in New York State; controls comprised 12,436 randomly chosen normal births. For each address at birth, the authors assigned a probability of exposure to solvents, metals, and pesticides from hazardous waste sites in the study area (n = 643). They also rated residences by proximity to air releases from industrial facilities and by contamination of community water supplies. Compared with individuals for whom a low probability of exposure existed, mothers who resided in areas assigned a medium or high probability of exposure to hazardous waste contaminants did not show an increased risk of either type of birth defects. After adjusting for mother's race and age, prenatal care initiation, and population density, the resulting relative risks were as follows: central nervous system defects and exposure to solvents, 0.8 (95% confidence interval [CI] = .4, .6); central nervous system and metals, 1.0 (95% CI = 0.7, 1.7); musculoskeletal defects and solvents, 0.9 (95% CI = 0.5, 1.3); and musculoskeletal defects and pesticides, .8 (95% CI = .5, 1.3). With respect to central nervous system defects, there was an elevated risk associated with living near industrial facilities that emitted solvents (odds ratio = 1.3 [95% CI = 1.0, 1.7]) or metals (OR = 1.4, [95% CI = 1.0, 1.8]) into the air. The low proportion of individuals who had a medium or high probability of residential exposure to hazardous waste-site contaminants limited the investigation of particular pathways, disease subgroups, and/or geographic areas. Associations between central nervous system defects and industrial releases of solvents and metals need to be investigated further.

Comparison of demographic and defect characteristics among different developmental stages of congenital limb reduction defects.

This study investigates how the timing of the development of limb reduction defects (LRDs) is associated with selected demographic, medical variables and defect characteristics. The LRD cases (n = 281) were ascertained from the Congenital Malformations Registry of New York State among 1983-1987 births. Cases were classified according to five stages of gestation based on when their earliest LRD developed. A control group consisted of a systematic random sample (n = 327) of non-malformed livebirths. Demographic and LRD characteristics were abstracted from birth certificates and medical charts. Among LRDs, the defects that occurred in the earlier stages of gestation were found to be more complex problems, compared with those developing in the later stages. Middle or late stage LRDs tended to occur more often with syndactyly than early stage LRDs, and had significantly higher frequencies of non-white infants compared with controls. In addition, some perinatal complications, pre-term delivery and low birthweight were positively associated with any LRD. Our findings suggest that the timing of a disturbance in limb development is important in terms of LRD characteristics. Demographics did not vary consistently with the stage of LRD development. Further studies testing this classification technique are suggested.

Fertility rates among lead workers and professional bus drivers: a comparative study.

We examined the relationship between lead exposure and fertility among men in a retrospective cohort study. Fertility (1981-1992) of lead-exposed workers was determined from birth certificate information and was compared with that of nonexposed workers. The exposed group consisted of 4256 reproductive-age male workers reported to the New York State Heavy Metals Registry. The comparison group consisted of a random sample of male bus drivers licensed in the state of New York; these men were frequency-matched by age and residence to the men who were exposed to lead. The actual number of births among lead workers was lower than the expected number of births for that group (standardized fertility ratio [SFR] = 0.88; 95% confidence interval [CI] = 0.81-0.95), especially among those who had elevated blood lead levels for longer than 5 years (SFR = 0.43; 95% confidence interval [CI]: = 0.31, 0.59). Even after adjusting for age, race, education, and residence, workers with > 5 years of exposure had reduced likelihood of fathering a child than those with a shorter period of exposure (relative risk, 0.38; 95% CI: 0.23, 0.61). Our study indicates that men with a long duration of lead exposure might have reduced fertility.

Potential parental exposure to pesticides and limb reduction defects.

OBJECTIVES: The goal of the study was to examine the effects of the potential pesticide exposure of parents on the risk of limb reduction defects in their offspring. METHODS: A case-referent study was conducted utilizing New York State Congenital Malformation Register data. Persons with limb reduction defects and referents were compared in terms of parental occupations and residence counties. Parental occupations and industries reported on birth certificates were qualitatively rated by industrial hygienists to estimate potential pesticide (list four groups) exposures. Residential exposures were estimated from agricultural census data according to county of residence. RESULTS: Neither parental exposure to pesticides [odds ratio (OR) 0.9, 95% confidence interval (95% CI) 0.6-1.4] nor farming occupation (OR 1.1, 95% CI 0.5-2.7) had an effect on the risk of total limb reduction defects. Those persons with limb reduction defects who had additional defects showed weak but consistent elevated risks in relation to parental occupational pesticide exposure. However, isolated cases of limb reduction defects were negatively related to these exposures. Residence in a farming or high pesticide use county was not associated with any type of limb reduction defect. CONCLUSIONS: Cases of limb reduction defect with additional malformations appear to be associated with parental occupational pesticide exposure. Improving exposure classifications and subdividing the limb reduction defects by types in the analyses are suggested for future research.

Examining potential demographic risk factors for congenital cardiovascular malformations on a time-developmental model.

A descriptive epidemiological study of congenital cardiovascular malformations (CCM) was performed to evaluate the use of a model which groups selected cardiac lesions according to time of embryonic origin. Infants born from 1983-1986 to residents of New York State excluding New York City and reported to the Congenital Malformation Registry (CMR) were first grouped into those with (n = 299) and without (n = 4424) chromosomes anomalies. Infants were then categorised according to the time of gestation of their earliest occurring CCM into one of the seven cardiac groups of the model. The categories were analysed by infant race, gender, birthweight, gestation, maternal age and education, and the presence of additional malformations. The group without chromosomal anomalies showed an increasing proportion of non-whites, females, and preterm births and a decreasing proportion of infants with other malformations in the embryonically later categories. The group with chromosomal anomalies was too small to exhibit any significant demographic patterns. The findings suggest associations between characteristics of the infant and the embryonic period in which the CCM occurred, thus demonstrating the usefulness of a time-based model. Further research should concentrate on confirming these associations with more complete data and on investigating their biological bases.

Evaluation of congenital limb reduction defects in upstate New York.

Limb reduction defects (LRD), reported to the Congenital Malformations Registry in upstate New York between 1983-1987, were investigated in terms of LRD classification, parental demographics, and LRD characteristics. After excluding LRD with chromosome abnormalities, we followed guidelines developed by the European Congenital Anomaly Surveillance Consortium (EUROCAT) to classify 271 LRD into six groups based on similar patterns of embryological failure. The descriptive analysis indicated a prevalence of 0.45 per 1,000 births (stable over 5 years) for LRD diagnosed during the first 2 years of life. Among 271 LRD cases, 95 were classified as terminal transverse (35.1%), 71 as split limbs (26.2%), 36 as preaxial (13.3%), 32 as postaxial (11.8%), 26 as intercalary (9.6%), and 11 as multiple types (4.1%). In cases with multiple limb involvement (28.4%), two thirds had the same type of LRD in each limb. The multiple types and preaxial groups showed the most distinctive characteristics: they had the highest frequency of suspected syndromes, other birth defects, and syndactyly compared to the other LRD. There were no significant differences in the distribution of demographic variables among different LRD types. Consideration of the incidence and characteristics of LRD by classifying them into these distinct subgroups may be useful for evaluating possible mechanisms of malformation.

Residential exposure summary methodology for a reproductive health study of multiple hazardous waste sites.

Evaluation of associations between residence near hazardous waste sites and rare outcomes requires the consideration of large geographic areas and multiple sources of contamination. For a case-control study of birth defects and solvents, metals and pesticide exposure, the authors rely on previously collected data to rate possible residential exposure from hazardous waste sites. Four pathways of exposure are evaluated: air vapor, air particulates, groundwater ingestion, and groundwater inhalation. Areas within one mile of each site are classified according to 1) the probability of exposure to solvents, metals, and pesticides, and, if available, 2) the relative concentration of contaminants. The probability of exposure (low, medium, or high) for air vapor and particulates depends on the evaporation and soil retention potential of the contaminants, degree of containment, predominant wind direction, and size of the contaminated area. The probability of exposure for groundwater ingestion and inhalation depends on whether there are water supply wells or affected basements within one mile, solubility of the contaminants, direction of groundwater flow, and groundwater sampling results. Relative concentration is based on sampling results for the most commonly sampled media. Exposures are shown on a standard template that defines 25 sectors within a 1 mile radius of each site. The method cannot provide exact estimates of residential exposure, because it relies on data of variable quality. It does provide a basis for evaluating health effects at multiple sites by identifying susceptible residential areas.

Comparison of mother's occupation and industry from the birth certificate and a self-administered questionnaire.

Maternal occupations recorded on birth certificates are a potential data source for evaluation of reproductive hazards, but may not accurately identify jobs held during the sensitive first trimester. Mothers' occupation and industry during 1 month before and 3 months after conception were reported on 1,760 mailed questionnaires. These were compared to mothers' most recent occupation and industry recorded on birth certificates. Overall, 72% of occupations and 77% of industries reported on the birth certificate agreed with that recorded on the questionnaire. Agreement was similar for mothers of normal and malformed infants. Among those that did not agree, 344 (75%) disagreed on the mother's employment status during the periconceptional period, rather than the actual occupation. For surveillance and hypothesis-generation using birth certificate data, it is important to obtain a correct description of whether the mother held a job outside the home during sensitive periods of her pregnancy.

Investigation of a testicular cancer cluster using a case-control approach.

A case-control methodology was developed and utilized to investigate a reported cluster of testicular cancer among leather workers in New York. Eighteen cases of testicular cancer, including the three index cases, diagnosed from 1974 to 1986 among residents of two counties with substantial leather tanning and finishing establishments made up the case group. Controls (n = 259) consisted of men of similar age who had been diagnosed with cancers of all other sites during the same time period. Reports of usual occupation for cases and controls, obtained from cancer registry reports and death certificates, indicated that cases were much more likely to be leather workers (28%) than controls (7%). After adjustment for age, the relative risk estimate for occupation and testicular cancer was 7.2 (95% Cl: 1.9-27.7). The association was further supported by occupational histories showing similar work environments within the leather industry for five out of six cases known to have been leather workers. Case-control analysis of a reported cluster does not provide independent confirmation of an association between occupational factors and testicular cancer. The methodology, however, can provide a timely way to evaluate the significance of occupational cancer clusters.

Occupational influences on reproduction: a review of recent literature.

There has been great interest in reproductive impairment, estimated to affect 30% of US couples, but the proportion of such problems resulting from occupational exposures remains unknown. This interest has spawned numerous papers that investigate the relationship between occupation and reproduction. Updating a previous review, the authors provide here a comprehensive listing of the literature published between 1981 and 1985 on this topic. Our critical review reveals common weaknesses, including (1) inadequate sample size and poor response rates, (2) potential for selection bias, (3) inadequate attention to potentially confounding factors, and (4) poor characterization of exposure.

Cancer mortality and solvent exposures in the rubber industry.

Some evidence suggests that solvent exposures to rubber industry workers may be associated with excess cancer mortality, but most studies of rubber workers lack information about specific chemical exposures. In one large rubber and tire-manufacturing plant, however, historical documents allowed a classification of jobs based on potential exposures to all solvents that were authorized for use in the plant. A case-control analysis of a 6678 member cohort compared the solvent exposure histories of a 20% age-stratified random sample of the cohort with those of cohort members who died during 1964-1973 from stomach cancer, respiratory system cancer, prostate cancer, lymphosarcoma, or lymphatic leukemia. Of these cancers, only lymphosarcoma and lymphatic leukemia showed significant positive associations with any of the potential solvent exposures. Lymphatic leukemia was especially strongly related to carbon tetrachloride (OR = 15.3, p less than .0001) and carbon disulfide (OR = 8.9, p = .0003). Lymphosarcoma showed similar, but weaker, associations with these two solvents. Benzene, a suspected carcinogen, was not significantly associated with any of the cancers.