Quantitative and Qualitative Strategies to Strengthen Internal Validity in Randomized Trials

2020 ◽  
pp. 084456212097419
Author(s):  
Souraya Sidani ◽  
Hannah O’Rourke

Although the randomized controlled trial (RCT) is the most reliable design to infer causality, evidence suggests that it is vulnerable to biases that weaken internal validity. In this paper, we review factors that introduce biases in RCTs and we propose quantitative and qualitative strategies for colleting relevant data to strengthen internal validity. The factors are related to participants’ reactions to randomization, attrition, treatment perceptions, and implementation of the intervention. The way in which these factors operate is explained and pertinent empirical evidence is synthesized. Quantitative and qualitative strategies are described. Researchers can plan to assess these factors and examine their influence, providing evidence of what actually contributed to the interventions’ causal impact.

2019 ◽  
Author(s):  
Mahesh Karra ◽  
David Canning

BACKGROUND The World Health Organization recommends that a woman waits at least 24 months after a live birth before getting pregnant again; however, an estimated 25% of birth intervals in low-income countries do not meet this recommendation for adequate birth spacing, and the unmet need for postpartum family planning (PPFP) services is high. Few randomized controlled trials have assessed the causal impact of access to PPFP services, and even fewer evaluations have investigated how such interventions may affect postpartum contraceptive use, birth spacing, and measures of health and well-being. OBJECTIVE This protocol paper aims to describe a randomized controlled trial that is being conducted to identify the causal impact of an intervention to improve access to PPFP services on contraceptive use, pregnancy, and birth spacing in urban Malawi. The causal effect of the intervention will be determined by comparing outcomes for respondents who are randomly assigned to an intervention arm against outcomes for respondents who are randomly assigned to a control arm. METHODS Married women aged 18-35 years who were either pregnant or had recently given birth were randomly assigned to either the intervention arm or control arm. Women assigned to the intervention arm received a package of services over a 2-year intervention period. Services included a brochure and up to 6 home visits from trained family planning counselors; free transportation to a high-quality family planning clinic; and financial reimbursement for family planning services, consultations, and referrals for services. Two follow-up surveys were conducted 1 and 2 years after the baseline survey. RESULTS A total of 2143 women were randomly assigned to either the intervention arm (n=1026) or the control arm (n=1117). Data collection for the first follow-up survey began in August 2017 and was completed in February 2018. A total of 1773 women, or 82.73% of women who were eligible for follow-up, were successfully contacted and reinterviewed at the first follow-up. Data collection for the second follow-up survey began in August 2018 and was completed in February 2019. A total of 1669 women, or 77.88% of women who were eligible for follow-up, were successfully contacted and reinterviewed at the second follow-up. The analysis of the primary outcomes is ongoing and is expected to be completed in 2021. CONCLUSIONS The results of this trial seek to fill the current knowledge gaps in the effectiveness of family planning interventions on improving fertility and health outcomes. The findings also show that the benefits of improving access to family planning are likely to extend beyond the fertility and health domain by improving other measures of women’s well-being. CLINICALTRIAL American Economics Association Registry Trial Number AEARCTR-0000697; https://www.socialscienceregistry.org/trials/697 Registry for International Development Impact Evaluations (RIDIE) Trial Number RIDIE-STUDY-ID-556784ed86956; https://ridie.3ieimpact.org/index.php?r=search/detailView&id=320 INTERNATIONAL REGISTERED REPORT DERR1-10.2196/16697


10.2196/16697 ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. e16697
Author(s):  
Mahesh Karra ◽  
David Canning

Background The World Health Organization recommends that a woman waits at least 24 months after a live birth before getting pregnant again; however, an estimated 25% of birth intervals in low-income countries do not meet this recommendation for adequate birth spacing, and the unmet need for postpartum family planning (PPFP) services is high. Few randomized controlled trials have assessed the causal impact of access to PPFP services, and even fewer evaluations have investigated how such interventions may affect postpartum contraceptive use, birth spacing, and measures of health and well-being. Objective This protocol paper aims to describe a randomized controlled trial that is being conducted to identify the causal impact of an intervention to improve access to PPFP services on contraceptive use, pregnancy, and birth spacing in urban Malawi. The causal effect of the intervention will be determined by comparing outcomes for respondents who are randomly assigned to an intervention arm against outcomes for respondents who are randomly assigned to a control arm. Methods Married women aged 18-35 years who were either pregnant or had recently given birth were randomly assigned to either the intervention arm or control arm. Women assigned to the intervention arm received a package of services over a 2-year intervention period. Services included a brochure and up to 6 home visits from trained family planning counselors; free transportation to a high-quality family planning clinic; and financial reimbursement for family planning services, consultations, and referrals for services. Two follow-up surveys were conducted 1 and 2 years after the baseline survey. Results A total of 2143 women were randomly assigned to either the intervention arm (n=1026) or the control arm (n=1117). Data collection for the first follow-up survey began in August 2017 and was completed in February 2018. A total of 1773 women, or 82.73% of women who were eligible for follow-up, were successfully contacted and reinterviewed at the first follow-up. Data collection for the second follow-up survey began in August 2018 and was completed in February 2019. A total of 1669 women, or 77.88% of women who were eligible for follow-up, were successfully contacted and reinterviewed at the second follow-up. The analysis of the primary outcomes is ongoing and is expected to be completed in 2021. Conclusions The results of this trial seek to fill the current knowledge gaps in the effectiveness of family planning interventions on improving fertility and health outcomes. The findings also show that the benefits of improving access to family planning are likely to extend beyond the fertility and health domain by improving other measures of women’s well-being. Trial Registration American Economics Association Registry Trial Number AEARCTR-0000697; https://www.socialscienceregistry.org/trials/697 Registry for International Development Impact Evaluations (RIDIE) Trial Number RIDIE-STUDY-ID-556784ed86956; https://ridie.3ieimpact.org/index.php?r=search/detailView&id=320 International Registered Report Identifier (IRRID) DERR1-10.2196/16697


Author(s):  
Janet L. Peacock ◽  
Sally M. Kerry ◽  
Raymond R. Balise

Chapter 12 covers all aspects of reporting a randomized controlled trial, and illustrates the use of the CONSORT statement and its checklist to report a trial. It discusses what is meant by intention-to-treat analysis. It considers the presentation of trials with other designs, particularly cluster randomized trials.


2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Debbie L. Cohen ◽  
LeAnne T. Bloedon ◽  
Rand L. Rothman ◽  
John T. Farrar ◽  
Mary Lou Galantino ◽  
...  

The prevalence of prehypertension and Stage 1 hypertension continues to increase despite being amenable to non-pharmacologic interventions. Iyengar yoga (IY) has been purported to reduce blood pressure (BP) though evidence from randomized trials is lacking. We conducted a randomized controlled trial to assess the effects of 12 weeks of IY versus enhanced usual care (EUC) (based on individual dietary adjustment) on 24-h ambulatory BP in yoga-naïve adults with untreated prehypertension or Stage 1 hypertension. In total, 26 and 31 subjects in the IY and EUC arms, respectively, completed the study. There were no differences in BP between the groups at 6 and 12 weeks. In the EUC group, 24-h systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure (MAP) significantly decreased by 5, 3 and 3 mmHg, respectively, from baseline at 6 weeks (P< .05), but were no longer significant at 12 weeks. In the IY group, 24 h SBP was reduced by 6 mmHg at 12 weeks compared to baseline (P= .05). 24 h DBP (P< .01) and MAP (P< .05) decreased significantly each by 5 mmHg. No differences were observed in catecholamine or cortisol metabolism to explain the decrease in BP in the IY group at 12 weeks. Twelve weeks of IY produces clinically meaningful improvements in 24 h SBP and DBP. Larger studies are needed to establish the long term efficacy, acceptability, utility and potential mechanisms of IY to control BP.


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