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Synthesize included studies

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Saved by Quan Nha HONG
on July 11, 2014 at 9:27:11 am
 

At the synthesis stage, results from included qualitative and quantitative studies are integrated and interpreted. Several techniques for synthesizing qualitative and quantitative results have been developed. Based on typical mixed methods research designs, three main types of synthesis designs are presented: (1) sequential exploratory, (2) sequential explanatory, and (3) convergent. The choice of the design depends on the review question(s). 

 

NEW (2014-07-11): We presented an exploratory study that aimed to check if these synthesis designs were found among a sample of mixed studies reviews (see abstract, see powertpoint presentation)

Reference: Hong, Q.N., Pluye, P. Can mixed methods designs be applied to mixed studies reviews? 2014 Mixed Methods International Research Association Conference. Boston (USA), June 27-29, 2014. 

 

1) Sequential exploratory synthesis

 

In sequential exploratory synthesis, the qualitative synthesis is followed by, and informs, the quantitative synthesis. The quantitative synthesis generalizes or tests findings derived the qualitative synthesis. Hence, there are two consecutive phases: phase-one Qualitative followed by phase-two Quantitative. In phase-one (qualitative), results of qualitative, quantitative and mixed methods studies are transformed into qualitative findings (e.g., types) using qualitative thematic analysis for instance. In phase-two (quantitative), results of quantitative studies are tabulated (pooled) and compared when there is a common entity across studies (e.g., an indicator for each type). Then, the interpretation of phase-one and phase-two results suggests new hypotheses and reveals knowledge gaps. 

 

 

Example adapted from Keating et al. (2011)

Phases Review question Output
Phase 1  Qualitative question: What are the views of COPD patients on the barriers and facilitators influencing the attendance to pulmonary rehabilitation?     Five major themes of barriers
Phase 2 Quantitative questions:  Is there any association between the level of up-take and completion of pulmonary rehabilitation by COPD patients and the identified barriers and facilitators? Odd ratio (association between factors identified in phase 1 and level of uptake and completion of the interventions)
Final integration    Impact of barriers and facilitators on uptake and completion of the intervention

 

Some mixed studies reviews that used a sequential exploratory synthesis: 

  • Keating A, Lee A,  Holland AE. (2011). What prevents people with chronic obstructive pulmonary disease from attending pulmonary rehabilitation? A systematic review. Chronic Respiratory Disease 8(2), 89-99. 
  • Mills EJ, Seely D, Rachlis B, Griffith L, Wu P, Wilson K, et al. (2006). Barriers to participation in clinical trials of cancer: a meta-analysis and systematic review of patient-reported factors. The Lancet Oncology, 7(2), 141-148.
  • Pluye P, Grad RM, Dunikowski LG, Stephenson R (2005). Impact of clinical information-retrieval technology on physicians: a literature review of quantitative, qualitative and mixed methods studies. International Journal of Medical Informatics, 74(9), 745-768.
  • Rosewilliam S, Roskell CA, Pandyan AD (2011). A systematic review and synthesis of the quantitative and qualitative evidence behind patient-centred goal setting in stroke rehabilitation. Clinical Rehabilitation, 25(6), 501-514.

 

2) Sequential explanatory synthesis

 

In sequential explanatory synthesis, the quantitative synthesis is followed by, and informs, the qualitative synthesis. The qualitative synthesis helps to explain some results of the quantitative synthesis. In phase-one (quantitative), results of quantitative studies and quantitative results of mixed methods studies are tabulated (pooled in evidence tables) for instance, and the presence and importance of differences in effects are measured (e.g., using meta-analysis technique when appropriate). In phase-two (qualitative), findings of qualitative studies and qualitative findings of mixed methods studies are synthesized using qualitative thematic analysis for instance. Then, the interpretation of phase-one and phase-two results suggests new explication and reveals knowledge gaps.

 

 

Example adapted from Campbell et al. (2011)

Phases

Review question

Output

Phase 1 

Quantitative question: For pregnant women, do diet and physical activity interventions prevent excessive gestational weight gain compared no intervention (e.g., routine prenatal care)?

 

Effect size

Phase 2

Qualitative question:  What are the viewpoints of pregnant women with regard to types of factors associated with the implementation and outcomes of diet and physical activity interventions preventing excessive gestational weight gain?

Three major themes relating to women's views of weight management in pregnancy

Final integration

 

Explanation of the success or failure of the intervention

 

Some mixed studies reviews that used a sequential explanatory synthesis: 

  • Campbell F, Johnson M, Messina J, Guillaume L, Goyder E (2011). Behavioural interventions for weight management in pregnancy: A systematic review of quantitative and qualitative data. BMC Public Health, 11.
  • Harden A, Brunton G, Fletcher A, Oakley A (2009). Teenage pregnancy and social disadvantage: systematic review integrating controlled trials and qualitative studies. British Medical Journal, 339, b4254.
  • Thomas J, Harden A, Oakley A, Oliver S, Sutcliffe K, Rees R, et al. (2004). Integrating qualitative research with trials in systematic reviews. British Medical Journal, 328(7446), 1010-1012.

 

3) Convergent synthesis

 

In convergent synthesis, results of included studies are complementary. The integration occurs for extracting and synthesizing these results using a transformation strategy. There are two categories of convergent synthesis design depending on the qualitative or quantitative nature of the data analysis.

 

First, there is a qualitative synthesis of results of qualitative, quantitative, and mixed methods studies (QUAL). In the data extraction for a qualitative synthesis, results of qualitative, quantitative, and mixed methods studies are transformed into themes such as constructs, concepts and factors. It is called qualitization of the data. Examples of convergent designs with qualitative synthesis: thematic synthesis, realist review, critical interpretive synthesis, meta-narrative synthesis, and multiple case synthesis. 

 

Second, there is a quantitative synthesis of results of qualitative, quantitative and mixed methods studies (QUAN). In the data extraction for a quantitative synthesis, results of qualitative, quantitative, and mixed methods studies are transformed into variables and values. It is called quantization of the data. Examples of convergent designs with quantitative synthesis: content analysis, Bayesian synthesis, and configurational comparative method. 

 

 

Example of convergent qualitative design adapted from Bélanger et al. (2011)

Review question

Processes

Output

Qualitative question: What are the (types of or key) processes of making shared decisions with palliative care patients?

Themes of qualitative studies (or qualitative part of mixed methods studies) are identified.

 

Variables used in quantitative studies (or quantitative part of mixed methods studies) are open coded qualitatively.

 

Then categories are developed.

Types of processes involved in shared decision making

 

Example of convergent quantitative design adapted from Buelens et al. (2008)

Review question

Processes

 

Quantitative question: What are the frequencies of the different paradigms and methods used in negotiation research studies in 1964-1993 compared to 1994-2004? 

Themes of qualitative studies (or qualitative part of mixed studies) are quantified according to their importance (or presence-absence) using a pre-defined quantification scheme.

 

Results of quantitative studies are synthetized using the same predefined quantification scheme.

Evolution of frequencies of paradigms and methods used

 

Some mixed studies reviews that used a convergent qualitative synthesis: 

  • Bélanger E, Rodríguez C, Groleau D (2011). Shared decision-making in palliative care: a systematic mixed studies review using narrative synthesis. Palliative Medicine, 25(3), 242-261.
  • Lewis SA, Noyes J, Mackereth S, Lewis SA, Noyes J, Mackereth S (2010). Knowledge and information needs of young people with epilepsy and their parents: Mixed-method systematic review. BMC Pediatrics, 10, 103.
  • Pedersen VH, Armes J, Ream E (2012). Perceptions of prostate cancer in Black African and Black Caribbean men: a systematic review of the literature. Psycho-Oncology, 21(5), 457-468.

 

Some mixed studies reviews that used a convergent quantitative synthesis:  

  • Buelens M, Woestyne M, Mestdagh S, Bouckenooghe D (2008). Methodological issues in negotiation research: A state-of-the-art-review. Group Decision and Negotiation, 17(4), 321-345.
  • Classen S, Lopez EDS (2006). Mixed methods approach explaining process of an older driver safety systematic literature review. Topics in Geriatric Rehabilitation, 22(2), 99-112.

 

Which synthesis design should we choose?  

We presented a workshop on this wikitool at the 2013 North American Primary Care Research Group (NAPCRG) Annual Meeting. One participant suggested the following flowchart:  

 

 

 

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