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Results for “Effect Modifier, Epidemiologic”

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On the association between date of birth and pollen sensitization: is age an effect modifier?

An association between date of birth and development of allergy has been proposed by prior research. Yet, the presence of a dose-response relationship or any potential effect modification for this association has not been widely studied. The aims of our study were to investigate whether an association between birth during pollen season and symptomatic sensitization to pollens exists, whether this association is stronger for patients with high rather than low allergic reactivity to pollens, and whether this association is modified by the age of the patients. Among 3318 asthmatic and/or rhinitic outpatients, we selected 805 patients sensitized exclusively to pollens (78 with low reactivity [LR] and 727 with high reactivity [HR]) and 629 patients with negative skin-prick tests (SPT) (control group). The association between being born during pollen season (February-July) and each of the pollen reactivity levels was assessed by estimating the odds ratios (OR). HR pollinosis patients were more likely than SPT negative patients of being born in February-July (OR 1.38, 95% Confidence Intervals (CI) 1.11-1.71). The likelihood of having been born in pollen season significantly increased across the levels of reactivity to pollens (HR > LR > SPT negative). These findings were valid only among patients with an early onset of symptoms. Although the OR for being born in pollen season was 1.91 (95% CI 1.32-2.77) for HR pollinosis patients with onset of symptoms < or = 15 years, it was 1.13 (95% CI 0.87-1.48) for those with later onset of symptoms (test of homogeneity: p = 0.026). Our results suggest that the exposure to allergenic pollens in the first months of life increases the risk of developing clinically relevant sensitization to them, particularly in the first 15 years of life.

Adolescent↗
PubMed1992

Synthesis of research findings through meta-analysis.

Meta-analysis is an alternative, quantitative approach to the analysis and synthesis of multiple investigations of the same clinical question. The statistical approaches that have been developed since Glass coined the term meta-analysis in 1976 are discussed. Clinicians will find meta-analysis helpful when there are conflicting research findings about perplexing clinical problems.

Bias↗
PubMed1992

The effects of cluster sampling in an African urban setting.

Cluster sampling was popularised by the sampling procedure promoted by the WHO/UNICEF for the evaluation of the expanded programme of immunisation (EPI). Without a clear understanding of the limitations of the sampling strategy used, this sampling strategy has been extended to other types of surveys. This article shows how to approach the assessment of cluster sampling techniques scientifically by calculating design effects (DEFFs) and rates of homogeneity (roh) and illustrates this scientific assessment with three case studies from Alexandra in South Africa. We report on the DEFFs and rohs for variables studied in these surveys. The DEFF for all the variables relating to housing tended to exceed two and was as high as 6.99 for the variable new development. The variables relating to health service utilisation and health practices, namely immunisation status, nutrition status, presence of Road to Health Cards (RTDCs), breast-feeding and knowledge of diarrhoea and oral rehydration all had a DEFF close to one. The variables relating to contraception use, literacy and schooling had DEFFs close to one and a half. For a few variables the DEFFs were below one and the rates of homogeneity less than zero. The highest values of roh were for environment factors (all above 0.1433). Rohs for factors related to utilization of PHC services were mostly between 0.0200 and 0.0499. No single class of factors seemed to be related to very low values of roh. These results are then discussed.

Cluster Analysis↗
PubMed2004

Multilevel health promotion research: conceptual and analytical considerations.

Health promotion research is often conceptualized through the use of socioecological frameworks. This results in data or variables associated with multiple levels such as individual, community, and provincial. These data are nested, or clustered. In other words, multilevel health promotion research is based on the idea that community influences health, above and beyond one's individual characteristics or behaviours. These contextual effects can be analyzed rigorously using multilevel modelling (MLM), thus determining whether contextual effects are truly derived from context or are the result of residents' social profile. MLM also facilitates examination of cross-level interaction effects. The authors discuss conceptual and methodological issues related to multilevel research. While multilevel pathways to health outcomes have been suggested at the conceptual level, analytical techniques that produce only average overall effects fail to reveal the various other influences on health behaviour.

Data Interpretation, Statistical↗
PubMed2003

The dilemma of early intervention: some problems in mental health screening and labeling.

Motivated in part by a desire to identify and manage individuals considered to be at risk for serious mental disorders, early intervention programs are becoming increasingly accepted by the medical community, increasingly supported by the pharmaceutical industry, and increasingly unchallenged by the public. This article examines some of the conceptual and practical difficulties associated with early, or preventive, mental health care. Examples are drawn from contemporary research as well as historical commentaries in the fields of industrial psychology, sociology, and education. The tone of the discussion is cautionary, but the goal is to encourage mental health professionals and consumers to consider the potential harmfulness of early intervention strategies before these programs are uncritically copied, expanded, or renewed.

Effect Modifier, Epidemiologic↗
PubMed2004

Statistical and clinical significance: alternative methods for understanding the importance of research findings.

Statistical significance is an important tool for interpreting a study's results, but statistical significance provides an incomplete picture of results. The likelihood of obtaining statistically significant results can be manipulated by a researcher who uses large sample sizes or who compares treatments that are expected to differ greatly in outcome. Measures of effect size provide an additional tool for understanding the results of a study and evaluating the importance of the results. Meta-analyses and estimates of clinical significance can also help clinicians properly evaluate research findings.

Bias↗
PubMed2006

The safety of safety research: the case of patient fall research.

Most fall intervention programs consist of 2 components: fall risk prediction instruments to identify the patient who is likely to fall, and fall intervention strategies to prevent the patient from falling or to protect the patient from injury should a fall occur. While critical to the effectiveness of a fall intervention program, many of the fall risk prediction instruments have been criticized for their failure to accurately identify the fall-prone patient. In this article, in the context of the validity assessments conducted on the Morse Fall Scale, the research conducted in the past 2 decades on fall risk assessment is critiqued. Some fall prediction research is based upon invalid assumptions and/or errors in design, both in the development of risk scales and in the evaluation of these instruments. Many of these instruments have been constructed with inappropriate reliance on face validity, have been evaluated inadequately, or have been tested in the clinical setting using an invalid design. Finally, improper use of fall scales in the clinical area may increase the risk of injury to the patient. The author concludes that much nursing research on patient falls does not contribute to improved patient safety.

Accident Prevention↗
PubMed1994

Risk indicators in the psychosocial and physical work environment for work-related neck, shoulder and low back symptoms: a study among blue- and white-collar workers in eight companies.

The study was based on a questionnaire and included 209 white-collar workers and 241 blue-collar workers in eight companies. The questionnaire deals with musculoskeletal symptoms, psychosocial and physical load factors. The relationship between job factors and neck, shoulder and low-back symptoms was analysed. The Nordic Musculoskeletal Questionnaire (NMQ) was supplemented with an additional question regarding whether or not the symptoms were believed to be related to work. The associations between the psychosocial factors and musculoskeletal symptoms were substantially higher when solely work-related symptoms were included in the analyses; these associations were of the same magnitude as that between several physical work load factors and work-related musculoskeletal symptoms. This study suggests that calculations of associations based solely on the NMQ, without the inclusion of questions to elicit reports of symptoms that are believed to be work-related, could have a powerful effect-masking consequence.

Effect Modifier, Epidemiologic↗
PubMed1994

Effects of low-dose iron supplementation in women with low serum ferritin concentration.

We studied effects of dose and treatment duration during low-dose iron supplementation in premenopausal, non-pregnant women, with initial serum ferritin and haemoglobin concentrations < 20 micrograms x l-1 and > or = 120 g x l-1, respectively. The study was randomized, double-blind and placebo-controlled. Three groups completed a 6-month study: placebo (n = 27), FE-9 (9 mg iron x day-1, n = 18) and FE-27 group (27 mg iron x day-1, n = 19). The supplement consisted of 11% heme and 89% inorganic iron. In FE-27, serum ferritin increased from (mean, 95% confidence interval) 11.8 (9.7; 14.4) to 25.3 (18.6; 34.4) micrograms x l-1 in 1 month, and remained stable after that (ANOVA: group effect, P = 0.0003). In both FE-9 and FE-27, blood haemoglobin levels increased from 136 (132; 140) to 142 (139; 145) g x l-1 in 1 month, remaining constant after that (group effect, P = 0.001). Hence, the 27 mg daily dose of organic/inorganic iron corrected both mild anaemia and storage iron depletion, whereas the 9 mg dose did not affect iron stores. Elongation of treatment duration above 1 month brought about only minor changes.

Adult↗