Examining theoretical models through research synthesis. The benefits of model-driven meta-analysis.

Quantitative research synthesis methods can be used to examine theoretical models for substantive research questions. Model-driven syntheses can address more complex questions than have typically been addressed in quantitative reviews in a more systematic and organized manner than in a traditional narrative review. A rationale and set of objectives for syntheses involving models are reviewed. The author describes how to incorporate models into each stage of a review, outlining problems and limitations that may arise at each stage. Examples from several model-driven syntheses illustrate the points made in the article.

Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group.

OBJECTIVE: Because of the pressure for timely, informed decisions in public health and clinical practice and the explosion of information in the scientific literature, research results must be synthesized. Meta-analyses are increasingly used to address this problem, and they often evaluate observational studies. A workshop was held in Atlanta, Ga, in April 1997, to examine the reporting of meta-analyses of observational studies and to make recommendations to aid authors, reviewers, editors, and readers. PARTICIPANTS: Twenty-seven participants were selected by a steering committee, based on expertise in clinical practice, trials, statistics, epidemiology, social sciences, and biomedical editing. Deliberations of the workshop were open to other interested scientists. Funding for this activity was provided by the Centers for Disease Control and Prevention. EVIDENCE: We conducted a systematic review of the published literature on the conduct and reporting of meta-analyses in observational studies using MEDLINE, Educational Research Information Center (ERIC), PsycLIT, and the Current Index to Statistics. We also examined reference lists of the 32 studies retrieved and contacted experts in the field. Participants were assigned to small-group discussions on the subjects of bias, searching and abstracting, heterogeneity, study categorization, and statistical methods. CONSENSUS PROCESS: From the material presented at the workshop, the authors developed a checklist summarizing recommendations for reporting meta-analyses of observational studies. The checklist and supporting evidence were circulated to all conference attendees and additional experts. All suggestions for revisions were addressed. CONCLUSIONS: The proposed checklist contains specifications for reporting of meta-analyses of observational studies in epidemiology, including background, search strategy, methods, results, discussion, and conclusion. Use of the checklist should improve the usefulness of meta-analyses for authors, reviewers, editors, readers, and decision makers. An evaluation plan is suggested and research areas are explored.

The efficacy of medical abortion: a meta-analysis.

Multiple clinical studies demonstrate the efficacy of medical abortion with mifepristone or methotrexate followed by a prostaglandin analogue. However, assessing predictors of success, including regimen, is difficult because of regimen variability and a lack of direct comparisons. This meta-analysis estimates rates of primary clinical outcomes of medical abortion (successful abortion, incomplete abortion, and viable pregnancy) and compares them by regimen and gestational age. We identified 54 studies published from 1991 to 1998 using mifepristone with misoprostol (18), mifepristone with other prostaglandin analogues (23), and methotrexate with misoprostol (13). Data abstracted from studies included regimen details and clinical outcomes by gestational age. We found that efficacy decreases with increasing gestational age (p<0.001), and differences by regimen are not statistically significant except at gestational age > or =57 days. For gestations < or =49 days, mean rates of complete abortion were 94-96%, incomplete abortion 2-4%, and ongoing (viable) pregnancy 1-3%. For gestations of 50-56 days, the mean rate of complete abortion was 91% (same for all regimens), incomplete abortion 5-8%, and ongoing pregnancy 3-5%. For > or =57 days, success was lower for mifepristone/misoprostol (85%, 95% confidence interval 78-91%) than for mifepristone/other prostaglandin analogues 95% (CI 91-98%, p = 0.006). For mifepristone/misoprostol, using > or =2 prostaglandin analogue doses seems to be better than a single dose for certain outcomes and gestational ages. We conclude that both mifepristone and methotrexate, when administered with misoprostol, have high levels of success at < or =49 days gestation but may have lower efficacy at longer gestation.

PIP: Multiple clinical studies demonstrate the efficacy of medical abortion with mifepristone or methotrexate followed by a prostaglandin analogue. However, assessing predictors of success, including regimen, is difficult because of regimen variability and a lack of direct comparisons. This meta-analysis estimates rates of primary clinical outcomes of medical abortion (successful abortion, incomplete abortion, and viable pregnancy) and compares them by regimen and gestational age. The authors identified 54 studies published from 1991 to 1998 using mifepristone with misoprostol (18), mifepristone with other prostaglandin analogues (23), and methotrexate with misoprostol (13). Data abstracted from studies included regimen details and clinical outcomes by gestational age. The authors found that efficacy decreases with increasing gestational age (p 0.001), and differences by regimen are not statistically significant except at gestational age 57 days or more. For gestations of 49 or fewer days, mean rates of complete abortion were 94-96%, incomplete abortion 2-4%, and ongoing (viable) pregnancy 1-3%. For gestations of 50-56 days, the mean rate of complete abortion was 91% (same for all regimens), incomplete abortion 5-8%, and ongoing pregnancy 3-5%. For 57 days or more, success was lower for mifepristone/misoprostol (85%; 95% CI, 78-91%) than for mifepristone/other prostaglandin analogues (95%; 95% CI, 91-98%; p = 0.006). For mifepristone/misoprostol, using 2 or more prostaglandin analogue doses seems to be better than a single dose for certain outcomes and gestational ages. The authors conclude that both mifepristone and methotrexate, when administered with misoprostol, have high levels of success at 49 or fewer days.

Parental factors and the young child's postdivorce adjustment: a meta-analysis with implications for parenting arrangements.

A model-based meta-analytic review highlighted relationships critical for understanding the young child's postdivorce adjustment when planning parenting arrangements. This review confirmed the utility of an interactional model that includes preseparation information and information about father, mother, and the parental alliance. Interactions among the quality and frequency of father's involvement in relation to postdivorce child adjustment that were not clear in studies looking only at direct effects of father-access variables were identified. Results indicated that maternal variables should not be viewed in isolation from the parental alliance or from the father-child relationship. The review discusses variables promoting developmental competence as well as risk factors that clearly interfere with both parental and child functioning.

Documenting English syntactic development in face-to-face signed communication.

The authors explored the face-to-face English competence of five students who were participating in a larger study of teachers' use of English-based signing. Using case studies, the authors report on the students' development of English-based signing at the beginning and end of their involvement in this 4-year study. Grammatical forms similar in English and American Sign Language (ASL) were initially more readily produced when tested for in English, and showed consistently higher attainment levels across all the students, than grammatical forms that are different in English and ASL. The authors found emerging English forms that could be documented (a) between prompted and imitated utterances and (b) within blocks of test items examining the same grammatical constructions. The authors conclude that teachers' concerted efforts to use English-based signing as a language of instruction enhance deaf students' English acquisition. Such signing helps build a bridge between native sign language and the development of English skills necessary for literacy.