Elsevier

Schizophrenia Research

Volume 179, January 2017, Pages 2-7
Schizophrenia Research

Revisiting the International Physical Activity Questionnaire (IPAQ): Assessing physical activity among individuals with schizophrenia

https://doi.org/10.1016/j.schres.2016.09.010Get rights and content

Abstract

Background: Individuals with schizophrenia tend to have low levels of physical activity (PA) which contributes to high rates of physical comorbidities. Valid and reliable methods of assessing PA are essential for advancing health research. Ten years after initial validation of the Short-Form International Physical Activity Questionnaire (IPAQ), this study expands on the initial validation study by examining retest reliability over a 4-week period, assessing validity with a larger sample, and comparing validity of the IPAQ to a 24-hour recall alternative.

Methods: Participants completed the IPAQ at baseline and 4 weeks later, along with a 24-hour PA recall at week 4. At week 3 participants wore waist accelerometers for 7 days. Spearman's correlation coefficients and Bland-Altman plots were calculated based on weekly minutes of moderate to vigorous PA (MVPA).

Results: Test-retest reliability for the self-administered IPAQ was ρ = 0.47, p < 0.001 for MVPA. Correlation between IPAQ assessment and accelerometer-determined MVPA was ρ = 0.30, p = 0.003. The 24-hour recall correlated significantly with MVPA on the previous day ρ = 0.27, p = 0.012. A Bland-Altman plot indicated the IPAQ-SF underreported by − 119.2 min (− 72%) on average compared to accelerometry (95% limits of agreement − 1017.1 to 778.7 min, − 292% to 147%).

Conclusion: Compared to previous IPAQ validation work in this population, criterion validity was similar, but reliability was lower over a 4-week period. MVPA criterion validity of the 24-hour recall was comparable to the 7-day self-report IPAQ. Findings further support that the IPAQ is a suitable assessment tool for epidemiological studies. Objective measures of physical activity are recommended for intervention assessment.

Introduction

In addition to the psychological symptoms of schizophrenia, individuals with the disorder suffer from high rates of obesity, diabetes, and cardiovascular disease compared to the general population (Dixon et al., 2000, Hennekens et al., 2005, Manu et al., 2015). These physical comorbidities contribute, in part, to the 15–25 year reduced life expectancy for people with schizophrenia (Laursen et al., 2012) as well as reduced quality of life (Faulkner et al., 2007, Foldemo et al., 2014, Guo et al., 2013, Sugawara et al., 2013). Physical activity (PA) is well established as an efficacious method of preventing and managing these physical illnesses in the general population (Orozco et al., 2008, Shaw et al., 2007, Thomas et al., 2009, Warburton et al., 2010). Testing methods for increasing PA among individuals with schizophrenia is therefore warranted (McNamee et al., 2013, Vancampfort et al., 2016). Essential to this is the need to accurately measure PA within the schizophrenia population in order to identify the prevalence of physical (in) activity, assess the effectiveness of PA interventions, and examine relationships between physical (in) activity and other outcomes of interest to researchers and clinicians (Vancampfort et al., 2016).

With the advent of wearable accelerometers it is now possible to objectively measure PA in the field, with good reliability and validity (Kelly et al., 2013), without direct observation of participants (LaPorte et al., 1985). However, to obtain accurate results, accelerometers present some burden to participants such as having to adhere to wearing the device for the duration of an assessment period (e.g., 1 week). Additionally, accelerometers are costly relative to self-report measures of PA. When objective measures such as accelerometry are not feasible, a common alternative is to use a subjective, self-report measure of PA (Soundy et al., 2014).

The International Physical Activity Questionnaire (IPAQ) (Craig et al., 2003) is one such subjective measure of PA. The IPAQ asks participants to self-report on the frequency, intensity (moderate, vigorous, walking, sitting) and duration over the past 7 days they have engaged in PA. The IPAQ is available as both a long and short-form paper survey in multiple languages, which allows for cross-cultural comparisons. The short-form version of the IPAQ has been previously assessed for its test-retest reliability and criterion validity with accelerometry among 35 outpatients with schizophrenia over a 1-week period (Faulkner et al., 2006). The authors reported test-retest reliability in the sample of Spearman's ρ = 0.68 (95% CI: 0.45–0.83) for minutes of moderate to vigorous PA (MVPA). Reliability of moderate PA (MPA) was ρ = 0.50 (95% CI: 0.20–0.70) and ρ = 0.69 (95% CI: 0.46–0.83) for vigorous PA (VPA). Criterion validity for MVPA with accelerometry was ρ = 0.37 (95% CI: 0.04–0.63). Overall, the authors concluded the psychometric properties of the IPAQ observed in this sample of individuals with schizophrenia was comparable to the pooled values reported by Craig et al. (2003) in the general population (reliability: pooled ρ = 0.76, 95% CI 0.73–0.77; validity: pooled ρ = 0.30, 95% CI 0.23–0.36). After ten years of use in the field, now is a timely opportunity to revisit the psychometric properties of the IPAQ within the schizophrenia population. This is particularly pertinent given efforts to develop a new self-report, physical activity measure for use among individuals with serious mental illness (Rosenbaum and Ward, 2016).

Understanding the reliability of the IPAQ over a longer period may be informative for exploring stability of physical activity in epidemiological research and estimating how much variation could be attributed to measurement error. Additionally, when initially evaluated by Faulkner et al. (2006), the IPAQ was aided by a structured recall lead by the experimenter, rather than being provided to the participant in questionnaire form, as is intended. An unstructured administration where the participant is simply presented with the questionnaire may result in different psychometric characteristics, especially in populations where cognitive impairment is prevalent.

Cognitive deficits among people with schizophrenia are common. It has been suggested that 75–85% of people with schizophrenia have some form of significant cognitive impairment (Reichenberg et al., 2006). Deficits in memory are common (Keefe and Fenton, 2007, Reichenberg et al., 2006), and may significantly impact participant's ability to accurately recall activities over an extended period without assistance. Furthermore, deficits in attention and executive function (Keefe and Fenton, 2007, Reichenberg et al., 2006) in conjunction with deficits in reading comprehension (Arnott et al., 2016, Hayes and O'Grady, 2003) may impact the reliability and validity of any self-report questionnaire.

An alternative to the IPAQ and other self-report questionnaires is having participants specifically recount their activities over the previous day through a detailed structured recall. Ostensibly having to remember only the most recent day in detail, rather than over a 7-day period, may be easier and thus provide a more accurate recall. In the general population, interview based protocols have demonstrated higher criterion validity for measuring PA than self-report measures (Sallis and Saelens, 2000). However, one potential disadvantage is that a 24-hour recall may not be as sensitive to regular activity patterns; for example, the previous day may not be representative of an individual's typical week.

In order to identify and develop more effective subjective tools in the measurement of PA among people with schizophrenia, the current study was undertaken to assess the psychometric properties of the IPAQ and a 24-hour structured recall compared to accelerometry. Specifically, data from a pre-existing prospective study was available to assess 1) the test-retest reliability of the self-administered short-form IPAQ over a 4-week time period, 2) the criterion validity of a self-administered IPAQ compared to accelerometry, and 3) the criterion validity of a 24-hour PA recall compared to accelerometry, in a sample of people with schizophrenia. It was hypothesized that longer periods between assessments would reduce the reliability when using the IPAQ, and that the self-administration of the IPAQ would result in lower levels of criterion validity than previously examined in Faulkner et al.'s (2006) validation work. Finally, the 24-h recall was expected to demonstrate stronger validity compared to the IPAQ.

Section snippets

Participants

Research ethics boards at the Centre for Addiction and Mental Health in Toronto and the University of Toronto approved the larger prospective study. To be included in the study, participants were required to: 1) be age 18–64 years (in line with the Canadian Physical Activity Guidelines recommendations for adults (Canadian Society of Exercise Physiology, 2012)), and 2) have a diagnosis of schizophrenia or schizoaffective disorder. The Mini-International Neuropsychiatric Interview (MINI) (Sheehan

Demographics

Table 1 summarizes demographics of the study participants.

IPAQ retest reliability

Table 2 summarizes the amount of PA reported in the week 1 and week 4 IPAQ-SF administrations. An initial 127 participants completed the week 1 IPAQ-SF, while 109 participants (86% of initial sample) completed the week 4 IPAQ-SF assessment. Table 3 reports the 4-week test-retest reliability of the IPAQ-SF. The Spearman correlation coefficient for minutes of MVPA per week was 0.47, p < 0.001, n = 107 and remained unaffected when inpatients

Discussion

Overall, results from the current study confirm and expand the psychometric results of the IPAQ-SF previously reported by Faulkner et al. (2006). Compared to this previous study, 4-week test-retest reliability of the IPAQ-SF was slightly lower than 1-week retest reliability in all categories of PA, but not outside of confidence interval estimates. These results indicate that, as expected, the IPAQ-SF may be less reliable over longer periods. The present study also expands previous knowledge by

Role of funding

This study was supported by a Canadian Institutes of Health Research (CIHR) operating grant #MOP-115709. Guy Faulkner is supported by a Canadian Institutes of Health Research-Public Health Agency of Canada Chair in Applied Public Health. The funding source did not have a role in study design.

Contributors

Dr. Faulkner, Dr. Arbour-Nicitopoulos, and Dr. Remington designed the study. Markus Duncan and Mehala Subramaniapillai performed data collection. Markus Duncan performed data analysis and prepared the manuscript.

Conflicts of interest

Dr. Remington has received consultant fees from Neurocrine Biosciences, Novartis, and Synchroneuron, as well as grant support from Novartis. All other authors declare that they have no conflicts of interest.

Acknowledgements

The authors would like to thank Carol Borlido for her role and assistance in recruiting participants to the study and collecting data.

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