Social predictors of adult asthma: a co-twin case-control study

BACKGROUND: Environmental factors are needed to explain the observed increase in the prevalence of asthma during recent decades, despite the existence of a recognised genetic component in asthma. A co-twin case-control study was undertaken to examine possible social risk factors for asthma. METHODS: Asthma diagnoses were based on register data of reimbursed asthma medication. During 17 years follow up of the Finnish twin cohort, 262 twin pairs discordant for incident asthma were identified. Conditional logistic regression for 1-1 matched data was used for risk calculation. RESULTS: The atopic twin had an increased risk of asthma compared with the non-atopic co-twin (RR 2.91, 95% CI 1.81 to 4.68). The more educated twin had a decreased risk of asthma compared with his/her twin sibling with less education (RR 0.45, 95% CI 0.23 to 0.86), and the twin who participated in conditioning exercise had a decreased risk of asthma compared with the more sedentary co-twin (RR 0.55, 95% CI 0.34 to 0.88). CONCLUSIONS: In addition to allergic diseases, educational level and physical activity are associated with adult onset asthma, which indicates a role for factors associated with life style.     

Home environment and asthma in Kenyan schoolchildren: a case-control study.

BACKGROUND--There is increasing evidence that environmental factors contribute to the development of asthma, so the relationship was studied between home environment factors and asthma among school children of varying socioeconomic backgrounds living in a developing country. METHODS--A case-control study was performed in participants of a prevalence survey which included 77 schoolchildren with asthma (defined by a history of wheeze, doctor diagnosis, or a decline in FEV1 of > or = 10% at five or 10 minutes after exercise) and 77 age and gender matched controls. Subjects were selected from 402 school children aged 9-11 years attending five primary schools in the city of Nairobi who participated in a prevalence survey of asthma. Visits were made to the homes of cases and controls and visual inspection of the home environment was made using a checklist. A questionnaire regarding supplemental salt intake, parental occupation, cooking fuels, and health of all children in the family was administered by an interviewer. RESULTS--In multivariate analysis the following factors were associated with asthma: damage caused by dampness in the child's sleeping area (adjusted odds ratio (OR) 4.9; 95% confidence interval (CI) 2.0 to 11.7), air pollution in the home (OR 2.5; 95% CI 2.0 to 6.4), presence of rugs or carpets in child's bedroom (OR 3.6; 95% CI 1.5 to 8.5). Children with asthma reported a supplemental mean daily salt intake of 817 mg compared with 483 mg in controls. CONCLUSIONS--Home environmental factors appear to be strongly associated with asthma in schoolchildren in a developing nation. These findings suggest a number of hypotheses for further studies.     

Usual dietary salt intake and asthma in children: a case-control study.

BACKGROUND: A decline in host resistance due to an alteration in diet--primarily of salt--was recently put forward as a possible explanation for rising rates of asthma. METHODS: A case-control study was conducted in participants in a prevalence survey which included 187 children with asthma (defined by prior diagnosis and/or a decline in forced expiratory volume in one second (FEV1) of > or = 10% after exercise) and 145 age and sex matched controls. Subjects were selected from 989 children aged 5-13 years attending 18 elementary schools on the island of Montreal. Usual dietary salt intake was estimated from a food frequency questionnaire administered to the mother, and a salt intake score was used to group the children into quartiles from I (lowest) to IV (highest salt intake). Bronchial hyperresponsiveness to methacholine was assessed by Yan's method. Cases and controls were combined in one group to examine the relationship of salt intake to bronchial hyperresponsiveness to methacholine. Methacholine responsiveness was expressed as a dose-response slope and ranks of dose-response slopes were used in the analysis. RESULTS: After accounting for important confounding variables, there was no association between asthma and salt intake, while methacholine dose-response slope ranks increased with increasing salt intake and methacholine responsiveness was greater in the highest quartile than in the lowest quartile of salt intake. The median dose-response slopes in % fall in FEV1 per mumol methacholine for quartiles I, II, III, and IV were 5.4, 5.9, 7.7, and 8.7. CONCLUSIONS: No association was found between asthma or exercise-induced bronchospasm and dietary salt intake. Bronchial hyperresponsiveness to methacholine did, however, appear to increase with greater salt intake, but the relevance of this association to asthma is unclear.     

Deaths certified as asthma and use of medical services: a national case-control study

BACKGROUND: Studies have linked asthma death to either increased or decreased use of medical services. METHODS: A population based case-control study of asthma deaths in 1994-8 was performed in 22 English, six Scottish, and five Welsh health authorities/boards. All 681 subjects who died were under the age of 65 years with asthma in Part I on the death certificates. After exclusions, 532 hospital controls were matched to 532 cases for age, district, and date of asthma admission/death. Data were extracted blind from primary care records. RESULTS: The median age of the subjects who died was 53 years; 60% of cases and 64% of controls were female. There was little difference in outpatient attendance (55% and 55%), hospital admission for asthma (51% and 54%), and median inpatient days (20 days and 15 days) in the previous 5 years. After mutual adjustment and adjustment for sex, using conditional logistic regression, three variables were independently associated with asthma death: fewer general practice contacts (odds ratio 0.82 (95% confidence interval (CI) 0.74 to 0.91) per 5 contacts) in the previous year, more home visits (1.14 (95% CI 1.08 to 1.21) per visit) in the previous year, and fewer peak expiratory flow recordings (0.83 (95% CI 0.74 to 0.92) per occasion) in the previous 3 months. These associations were similar after adjustment for markers of severity, psychosocial factors, systemic steroids, short acting bronchodilators and antibiotics, although the association with peak flow was weakened and just lost significance. CONCLUSION: Asthma death is associated with less use of primary care services. Both practice and patient factors may be involved and a better understanding of these may offer possibilities for reducing asthma death.     

A case-control study of deaths from asthma.

A population based case control-study was initiated in 1981 to identify risk factors for death from asthma. Over a two year period all deaths in the Auckland population possibly due to asthma, in people less than 60 years of age, were investigated. From the 47 people who died from asthma 44 who had useful reversibility of airways obstruction (records showing greater than 20% variability of peak flow or a history indicating equivalent variability of shortness of breath) before death were selected as cases for the study. Both hospital and community based controls were used. The cases were more likely than were the community controls to have had severe disease, a hospital admission or visits to a hospital emergency department in the previous year (odds ratios 4.4, 16.0, 8.5 respectively). The asthmatic patients who died were more likely than either group of controls to have had a previous life threatening asthma attack. Poor management of the disease and poor compliance on the part of the patient increased the risk of death. In addition, use of three or more types of asthma drug within the past year was associated with an increased risk of dying that was independent of disease severity. Of interest was a similarity between asthmatic patients admitted to hospital and those who died. Nevertheless, a history of a previous life threatening attack and a recent admission to hospital identified a group at high risk.     

Nutrition and prostate cancer: a case-control study

This one-to-one, age- and race-matched case-control study involved 181 histologically confirmed black prostate cancer patients and 181 controls seen at three major hospitals in Washington, DC, during the period 1979-1982. Personal interviews were conducted to obtain the number of times food items of specified serving size were consumed per week by cases and controls during the age periods 30-49 and 50 years and older. Then the average daily consumption of each of 18 nutrients per 1,000 calories was calculated. There was risk enhancement associated with increased intake of proteins, total fat, saturated fat, oleic acid, and vitamin A during the age period 30-49 years. The association was highly significant for vitamin A and approached statistical significance for the other four nutrients. A hypothesis based on disturbance of the zinc-retinol binding protein-vitamin A axis was put forward to explain the relative risk enhancement effect of vitamin A on prostate cancer.     

Parental smoking and childhood asthma: longitudinal and case-control studies

BACKGROUND—The relation of parental smokingto wheezing and asthma occurring after the first year of life wasassessed by a systematic quantitative review of case-control andlongitudinal studies, complementing earlier reviews of cross sectionalsurveys and wheezing in early childhood.
METHODS—Fifty one relevant publications wereidentified after consideration of 1593 abstracts selected by electronicsearch of the Embase and Medline databases using keywords relevant topassive smoking in children. The search was completed in April 1997 and identified six studies of asthma incidence, seven of prognosis, 22 case-control studies, and 10 case series addressing disease severity.
RESULTS—Maternal smoking wasassociated with an increased incidence of wheezing illness up to age 6 (pooled odds ratio 1.31, 95% CI 1.22 to 1.41), but less stronglythereafter (1.13, 95% CI 1.04to 1.22). The long term prognosis ofearly wheezing illness was better if the mother smoked. The pooled oddsratio for asthma prevalence from 14 case-control studies was 1.37 (95%CI 1.15to 1.64) if either parent smoked. Four studies suggest thatparental smoking is more strongly associated with wheezing amongnon-atopic children. Indicators of disease severity including symptomscores, attack frequency, medication use, hospital attendance, and life threatening bronchospasm were in general positively related to household smoke exposure.
CONCLUSIONS—The excessincidence of wheezing in smoking households appears to be largelynon-atopic "wheezy bronchitis" with a relatively benign prognosis,but among children with established asthma, parental smoking isassociated with more severe disease. This apparent paradox may bereconciled if environmental tobacco smoke is considered a co-factorprovoking wheezing attacks, rather than a cause of the underlyingasthmatic tendency.

     

Primary biliary cirrhosis and osteoporosis: a case-control study

Osteoporosis is a common complication of chronic liver disease, from cholestatic disorders to autoimmune, alcoholic, and posthepatitic cirrhosis. Osteoporosis appears more striking in patients with primary biliary cirrhosis (PBC) because the disease usually affects elderly women, who are naturally prone to osteoporosis. Our aims were (1) to compare the prevalence of osteoporosis (T-score <-2.5 SD) between PBC patients and a group of age-and sex-matched controls consisting of healthy subjects from the general population; and (2) to identify the main risk factors for the development of bone loss. Thirty-three women with PBC (mean age, 47.3 +/- 10.4 years) and 66 healthy subjects were enrolled in the study. Bone mineral density (BMD) was assessed at the lumbar spine by dual-photon X-ray absorptiometry. Bone metabolism was evaluated by measuring serum calcium corrected for serum albumin, 25-hydroxyvitamin D (25-OH vit D), parathyroid hormone, and osteocalcin. Vertebral fractures were analyzed using vertebral fracture assessment (VFA). The mean T-score was lower in the PBC group compared to healthy controls, with a significant statistical difference (-2.39 +/- 0.93 and -1.47 +/- 0.99 in lumbar spine and total hip, respectively, in the PBC group versus -0.99 +/- 0.51 and -0.56 +/- 1.14 in healthy controls (P < 0.001). The prevalence of osteoporosis was 51.5% in the PBC group versus 22.7% in healthy controls with a statistically significant difference (P = 0.004). BMD of the PBC group was significantly correlated positively with body mass index (BMI) and 25-OH vit D, and negatively with menopausal status, duration of disease, and parathyroid hormone (PTH) levels. Vertebral fractures were present in 9% of the patients. We found that osteoporosis is more prevalent in women with PBC than in the general population. BMI, menopausal status, duration of the disease, and vitamin D deficiency are the main risk factors for osteoporosis in this liver disease.     

Risk factors for eclampsia: a case-control study

OBJECTIVE: Our purpose was to characterize the risk factors of eclampsia in women with preeclampsia. PATIENTS AND METHODS: A case-control study was conducted at Monastir hospital to investigate risk factors for eclampsia between 1st January 1995 and 30th June 2000. Cases were matched to preeclamptic controls on a 2:1 ratio. Univariate analysis was used to determine which of the independent variables were significantly different between the groups. Those with significant differences were then entered into multiple logistic regression analysis to determine the characteristics that were independently related to eclampsia. RESULT: A total of 41 cases of eclampsia were ascertained from deliveries. The ratio of eclampsia cases to number of deliveries over the study period was 1.87 per 1000. The first seizures occurred at home in 59% of the cases. Univariate analysis revealed statistical significance for the following variables associated with eclampsia: systolic hypertension > or =160 mmHg and diastolic > or =110 mmHg, headache, visual symptoms, vivid deep tendon reflexes, proteinuria >3+ or >3 g d(-1), uric acid concentration > or =350 micromol l(-1), serum creatinine concentration >100 micromol l(-1) and aminotransferase aspartate >30 IU l(-1). A history of abortion appears to be the protective factor against eclampsia. However, with subsequent multivariate analysis, only vivid deep tendon reflexes and elevated uric acid concentration remained significant. CONCLUSION: These data indicate a need for improved prenatal care and medical attention focused on prodroms of eclampsia as well as the detection of preeclampsia to reduce the incidence of eclampsia.     

Epidemiology of prostatic cancer: a case-control study

A population-based case-control study of prostatic cancer in Alberta was undertaken to determine the risk factors associated with the disease. Cases were 382 newly diagnosed prostatic cancer patients and 625 controls, group-matched to the anticipated age distribution of the cases, chosen at random from the health insurance roster. Subjects were interviewed in their homes by using a pre-tested questionnaire including questions related to ethnic group, education, puberty, marital history, family history, residence, water supply, smoking, and diet. Factors significantly related to the risk of developing prostatic cancer included ethnic group (British high, Ukrainian low), education (elementary high, university low), age at first marriage (early high, late low), family history (high risk for those with relatives with prostatic cancer), and increased masculinity among the children of cases. The results with respect to smoking, occupation, medical history, birthplace, residence, water supply, and diet were generally negative.     

Seminal plasma magnesium and premature ejaculation: a case-control study

OBJECTIVE: To determine the relationship between premature ejaculation (PE) and serum and seminal plasma magnesium levels, in a case-control study. PATIENTS AND METHODS: Thirty-eight patients referred to the authors' urology outpatient clinic were evaluated in two groups; cases comprised 19 men complaining of PE, defined using the Diagnostic and Statistical Manual of Mental Disorders IV criteria and an intravaginal ejaculatory latency time (IELT) of <1 min, and a control group of 19 married men with a normal IELT. All men had a history taken, a systemic physical examination and laboratory studies. After organic and psychogenic disorders were excluded, the 19 patients were included in the study. Seminal plasma and serum magnesium levels were determined using atomic absorption spectrophotometry. RESULTS: The mean (sd) plasma magnesium level was 94.7 (10.9) mg/L in the cases and 116.7 (11.6) mg/L in the controls. There was a significant relationship between seminal plasma magnesium, but not the plasma level, and PE (P < 0.001 and 0.597 respectively). CONCLUSION: PE is significantly related with a lower level of seminal plasma magnesium. The pathological physiology of this relationship requires more investigation.     

Laparoscopic cholecystectomy and cirrhosis:a case-control study of outcomes

The incidence of gallstone disease in patients with cirrhosis is greater than that in healthy patients. Previous surgical literature reported greater morbidity and mortality in patients with cirrhosis with both open and laparoscopic cholecystectomy (LC). We compared our recent experience with LC in patients with cirrhosis and controls. A retrospective review was performed using the search terms, “cirrhosis” and “laparoscopic cholecystectoaiy” Forty-eight patients with cirrhosis were identified and randomly matched with healthy controls by age and sex. Four controls were assigned per patient with cirrhosis. Outcomes assessed included mortality, duration of surgery, length of hospital stay, blood transfusion requirement, postoperative complications, and need for conversion to open cholecystectomy. Forty-eight patients with cirrhosis and 187 healthy controls underwent LC. Child-Pugh classification of severity of liver disease was as follows: Child's class A, 38 of 48 patients; Child's class B, 10 of 48 patients; and Child's class C, 0 of 48 patients. Patients with cirrhosis had statistically significantly lower albumin levels (P = .0001) and prolonged prothrombin times (P = .05). Average duration of surgery for patients with cirrhosis was 1.71 versus 1.57 hours (P = .57) for controls. Average length of hospital stay for patients with cirrhosis was 6.47 versus 4.77 days (P = .152) for controls. Average number of units of blood transfused in patients with cirrhosis was 0.156 versus 0.0 units (P = .025) in controls. Complications occurred in 6 of 48 patients with cirrhosis (12.5%) and 8 of 187 controls (4.2%; P < .05). No child's class C patient underwent LC. Four patients with cirrhosis (8.3%) and no controls were converted to open cholecystectomy. No postoperative infections were noted. There was no mortality in either group. LC in patients with Child's class A and B cirrhosis is reasonably safe and shows no increase in morbidity or mortality or worsening of outcome. Further studies are required to evaluate the management of acute gallbladder disease in Child's class C patients.     

Post-transplant erythrocytosis and immunosuppression with cyclosporin: a case-control study

Review of 142 renal transplant recipients treated with cyclosporin and prednisolone revealed 23 patients with post-transplant erythrocytosis. The clinical characteristics of these patients were compared with 23 cyclosporin/prednisolone-treated control subjects matched for age, sex, and duration of transplant. Erythrocytosis developed between 6 weeks and 30 months (median 12 months) after transplant. It persisted in 16 patients and resolved spontaneously in five. In two patients the decrease in haematocrit was associated with acute leukaemia in one and sudden deterioration of renal function in the other. In the study group there were fewer HLA (A, B and DR) mismatches (P less than 0.05) and greater pretransplant haematocrit (P less than 0.01) than in the control group. Other clinical factors--previous allografts, panel reactive cytotoxic antibodies, duration and type of dialysis, transplant function, pre- and post-transplant blood pressure, number of rejection episodes, cyclosporin concentration and dose, smoking habits and use of diuretics--did not differ significantly between the two groups. In our experience, erythrocytosis in cyclosporin-treated patients is a relatively common phenomenon and does not, in general, resolve spontaneously. It is unrelated to transplant function or rejection episodes but affects patients with well-matched kidneys and elevated pretransplant haematocrit values.     

Lymphatic fistula after vascular reconstruction: a case-control study

A retrospective case-control study was carried out to assess the importance of lymphatic fistulas that develop after vascular reconstruction and to determine the risk factors associated with them. The authors compared 35 patients who had lymphatic fistula after vascular reconstruction with 70 control patients, taken from the same database. They found a significant difference between the two groups only in age and indication for surgery: lymphatic fistulas were more likely to develop in older patients and in patients who underwent aortobifemoral bypass for limb salvage rather than for claudication (p less than 0.05).