Nursing and Health Interventions. Souraya Sidani

copies of relevant sources are obtained for full review and, if considered to meet all preset criteria, are selected for inclusion in the literature review.

      6 Extracting data: Selected sources are carefully reviewed to extract methodological (e.g. type of design, sample size, study quality) and substantive (e.g. conceptual and operational definitions of the problem and determinants investigated, target population, main findings related to the experience of the problem and its association with determinants). The data extracted are incorporated in a database in preparation for synthesis of quantitative, qualitative, or both types of findings.

      7 Synthesizing data: Different strategies and techniques can be used to synthesize descriptive and correlational (representing the reported associations between determinants and the health problem) quantitative and qualitative findings, and to integrate quantitative and qualitative evidence (for detail, refer to Hong et al., 2017). The selection of a particular technique is informed by the type of data extracted, the number of studies included in the review, and the availability of resources needed to apply the technique.

TABLE 3.3 Narrative review of literature on determinants of insomnia.

Category of predictors	Results	Sources
Predisposing factors	Age: Older adults are prone to sleep disturbances (explanation: due to fragmented sleep or comorbid medical conditions) Gender: Women of all age groups have a higher prevalence of sleep problems than men	Kao et al. (2008), López‐Torres Hidalgo et al. (2012), Paparrigopoulos et al. (2010), Rybarczyk et al. (2013), Singareddy et al. (2012), Zhang et al. (2012)
Precipitating factors	Comorbidity: Having one or more chronic diseases (e.g. cancer, angina, multiple sclerosis); symptoms (e.g. pain); and sleep disorders (e.g. restless leg syndrome), increases the odds of experiencing sleep problems Psychological conditions: depressive symptomatology and perceived distress Social conditions: marital status, level of education and socioeconomic status	Dragiotti et al. (2018), Fernandez‐Mendoza et al. (2012), Gindin et al. (2014), López‐Torres Hidalgo et al. (2012), Rybarczyk et al. (2013) Gindin et al. (2014), Isaia et al. (2011), Paparrigopoulos et al. (2010), Pillai et al. (2014), Vgontzas et al. (2012). Gellis et al. (2005), López‐Torres Hidalgo et al. (2012), Moscou‐Jackson et al. (2016)
Perpetuating factors	Health behaviors: smoking, alcohol consumption, and limited engagement in physical activity	Colagiuri et al. (2011), Endeshaw and Yoo (2010), Fernandez‐Mendoza et al. (2012), Paparrigopoulos et al. (2010)
Factors identified by persons with insomnia	Worry, illness/discomfort Note: varied by age such as worry more frequently reported in early working life and illness by older adults	Armstrong and Dregan (2014)

The results of the literature review point to similarities or variations, across client populations, settings, and time occasions, in the experience of the health problem relative to its indicators and level of severity. They also identify the range of possible determinants and those most significant. They delineate the nature (direct or indirect); direction (positive or negative); and size (small, moderate, large) of the relationships among determinants and the health problem experience. The findings, particularly those synthesized from qualitative studies and from theoretical sources, provide probable explanations (why and how) of the relationships. Table 3.3 illustrates the results of a narrative review of the literature on the determinants of insomnia.

       Strengths

The advantages of literature reviews rest on grounding the understanding of the health problem on actual data obtained by multiple researchers, from different client populations under different contexts, using different designs and methods. Results that are consistent across populations, contexts, and research methods enhance the accuracy of the conceptualization of the problem. Comprehensive lists of indicators and determinants of the problem are generated, reflecting different but complementary perspectives. These comprehensive lists reduce the likelihood of omitting a potentially significant indicator or determinant. The range of the severity level with which the problem is experienced by different client populations and in different contexts is identified. Factors contributing to different levels of problem severity may be revealed. Discrepancies in findings point to variability in the problem experience. This empirical knowledge of the health problem is useful in directing the development of interventions and in identifying the need for tailoring the intervention to the characteristics of different client populations and contexts.

       Limitations

      The limitations of literature reviews relate to the (often limited) availability of well‐planned and executed studies that investigated the health problem. Where available, there is the potential for publication bias (Chan et al., 2014), non‐replication of findings, or having mixed or inconclusive findings, all of which weaken the confidence in the validity or accuracy of the generated knowledge, and hence its utility in informing the design of interventions (Ioannidis et al., 2014: Van Assen et al., 2015).

      3.3.2.2 Conduct of Primary Studies

       Overview

      The decision to conduct a primary study to understand the health problem is made when: (1) there is a small number of studies that investigated the problem, thereby limiting the knowledge of the problem experience and its determinants; (2) the quality of available studies is appraised as low, which may be related to a range of conceptual and methodological concerns, such as unclear definition of the health problem, omission of theoretically important determinants, and use of measures with questionable reliability and validity; and (3) available studies have not investigated the health problem in the client population and context of interest, raising questions about the relevance and applicability of available evidence to the target population and context.

      The primary studies can be prospective quantitative, qualitative, or mixed (quantitative and qualitative, concurrent, or sequential) method. Mixed‐method studies are promising in generating a comprehensive, in‐depth understanding of the problem as experienced by the target population in the particular context of interest.

       Methods

      The process for planning and conducting primary studies is well described in basic and advanced research textbooks, and is not reviewed here. However, some key considerations are briefly mentioned.

       The main focus of the study is on the health problem and its determinants, as experienced by the target client population in the context of interest.

       The study is designed to address the specific gap in knowledge about the problem as experienced by the target client population and the context of interest. Quantitative, cross‐sectional or longitudinal studies aim to: (1) describe the experience of the problem (e.g. frequency of occurrence, severity, most common indicators) and its determinants and consequences at one point in time, or changes in the problem experience and determinants over time; (2) examine factors that operate at different levels and contribute most significantly to the problem as experienced by the target client population and the context of interest; or (3) test the theory of the problem derived from relevant middle range theories or empirical evidence. Qualitative studies can be designed to: (1) generate inductively the conceptualization of the health problem held by the target client