Validation of the Pregnancy Physical Activity Questionnaire (PPAQ)

Introduction

The results of many studies confirm the positive effect of physical activity during pregnancy on the health of both mother and child [1]. Increased physical activity in pregnant women in conjunction with a proper diet was connected with a lower risk of excessive weight gain in pregnancy, cesarean delivery, macrosomia, and neonatal respiratory morbidity [2], had a positive effect on the concentration of cholesterol, C-reactive protein (CRP), and blood pressure [3], and reduced the risk of preeclampsia [4] and gestational diabetes [5]. Regular exercise helped to maintain cardiovascular fitness levels throughout pregnancy, recovery of shape after childbirth [6], and improved sleep quality in pregnant women [7]. In case of miscarriage, women who were physically active reported significantly lower symptoms of depression compared to women who were not active [8]. Physical activity in combination with a proper diet during pregnancy also reduced the risk of overweight and obesity in women after childbirth [9] as well as the risk of overweight and obesity in the later years of the child’s life [10].
Due to the significant impact of physical activity on the health of the mother and the child, it is important to use standardised methods of assessment, which give the opportunity to compare the results of studies conducted in different countries, to monitor trends in activity, and to assess the effectiveness of intervention programs. Methods for assessment of physical activity of a person can be divided into objective and subjective [11]. Objective methods using various types of motion sensors are preferred in the studies. Due to the high cost, they are not commonly used in cohort studies on a large scale. Increasingly used accelerometers also have their limitations. They are primarily associated with the inability to measure certain types of activities, e.g. water sports, cycling, and activities that first of all require movements of the upper parts of the body, as well as the inability to grasp the context of physical activity (e.g. walking while carrying a load or walking uphill). The main advantage of subjective methods is that they do not require complicated and expensive technical equipment, and they are not troublesome for the respondents, and therefore do not change their behaviour. They allow for a comprehensive assessment of the respondents’ physical activity related to all aspects of their life.
In 2004, Chasan-Taber et al. developed the Pregnancy Physical Activity Questionnaire (PPAQ), taking into account household/caregiving activities, occupational activities, sports/exercise activities, transportation activities, and inactivity. The PPAQ measures the frequency and duration of activities and gives an intensity value to each activity. The PPAQ has been translated into many languages and is used to study the physical activity of pregnant women in different countries [12–16].

Aim of the research

The aim of this study was validation of the Polish version of the PPAQ by determination of its reproducibility.

Material and methods

Organisation of studies and sampling

The studies were conducted from June 2014 to February 2015 among pregnant women living in the Świętokrzyskie Voivodeship. The studied sample was selected using a snowball method from among women attending childbirth classes. A total of 176 women were recruited. From the basic set, the data of two women (1% of the respondents) were removed, which were considered to be unreliable in terms of weekly physical activity according to the algorithm developed by a team of experts – the authors of the PPAQ [17] (Figure 1). The collected data was then verified and cleaned by removing the respondents due to incomplete personal data, unreliable information, and thick errors (so-called “outliers”). In this way, the data of 12 respondents were removed (7% of the sample). Finally, the basic set of data included 164 women aged 18 to 42 years (mean age: 28.0 ±5.0 years). During the first study, 17% of the women were in the first trimester, 56% in the second, and 27% in the third trimester of pregnancy. In the second study, conducted at intervals of two weeks after the first one, 6% women of the were in the first trimester, 58% in the second, and 36% in the third trimester of pregnancy. The characteristics of the research group are presented in Table 1.
The studies were conducted with the consent of the Bioethics Committee at the Faculty of Health Science of Jan Kochanowski University.

Characteristics of PPAQ questionnaire

The PPAQ questionnaire contains questions concerning physical effort, which includes 32 types of physical activity. Its first part related to physical activity in the household and any other unpaid work that could be done outside the house. The second part of the questionnaire included questions about the physical effort associated with transportation from place to place, including work, shopping, entertainment, etc. Transportation could be done by car, bus, train, tram, bicycle, and walking. The third part of the questionnaire concerned certain types of physical effort associated with recreation, sport, exercise, and entertainment as well as active recreation or leisure. The fourth part concerned physical effort associated with occupational work and learning in different positions.
The original language version of the questionnaire was translated into Polish in accordance with the international recommendations for adaptation of tests and questionnaires [18]. The next step was testing the translated version of the questionnaire in order to assess the understanding of the questions and the accuracy of the wording. As a result of this process, the final version of the questionnaire was established. Responses to the questionnaire ranged from 0 to 6 or more hours during the day or from 0 to 3 h during the week. A section of open questions appended at the end of the PPAQ allowed the respondents to add activities not listed in the questionnaire. Sleep time was not taken into account. The time spent for each physical activity included in the PPAQ reported by women was multiplied by its intensity, and as a result, for each of the activities, the associated average weekly energy expenditure (MET-h/week) was obtained. The METs values given in the Compendium of Physical Activity [19] were used to estimate the intensity of the other forms of activity included in the PPAQ. Activities with lower or higher intensity were summed up to obtain an average value of the total activity expressed in METs per hour during the week. Each activity was classified according to intensity into: sedentary (1.5 METs), light (1.5–3.0 METs), moderate (3.0–6.0 METs), or high (> 6.0 METs). Furthermore, for each of the aforementioned levels of activity, the average number of METs per hour during the week was calculated. Activities were also classified according to their type (household/caregiving activities, occupational activi­ties, sports and exercise activities, transportation), giving the average number of METs per hour during the week spent on each type.
Validation of the method for assessing physical activity by determining its reproducibility consists of comparison of the results of the assessment of the activity obtained using a validated method with the results obtained using the same method, which was repeated (comparison: “test-retest”), assuming that the test and retest measurement conditions were the same.

Statistical analysis

Statistical analysis was performed using the statistical package Statistica PL v. 10.0 from StatSoft. Compliance of the schedule of the studied characteristics with the normal schedule was checked using the Kolmogorov-Smirnov test. The values of the characteristics were expressed as average value (x) and their volatility in the standard deviation (SD) and the minimum value (min.) and the maximum value (max.). The repeatability of the questionnaire was verified by determining the Pearson correlation coefficient (r) between the results obtained for the same people in the first and second interview, thus determining the intra-subject variability. Intra-subject variability was analysed by comparing the average values of physical activity for the whole group using the Student’s t-test (T) for dependent samples.

Results

The questionnaire’s reproducibility was assessed in a group of 164 pregnant women. The median of physical activity in the first PPAQ interview was 113.9 MET h/week, while in the second interview it was slightly lower at 112.4 MET h/week (Table 2). No women in the first or second interview declared high physical activity (> 6.0 METs). The most common type of activity was light activity (1.5–3.0 METs). The respondents, both in the first and in the second interview, showed the highest activity in domains of household/caregiving. Comparison of the results obtained in the first and second study did not show significant differences in physical activity, with regard to any different level of intensity of physical activity (Table 3). For all levels of intensity, a high correlation between the results obtained in both interviews was found. The correlation coefficient for total physical activity was r = 0.96. The reproducibility of the results obtained from PPAQ questionnaire was the highest for inactivity, while the lowest was in the case of high-intensity activity (r = 0.72). In the analysis conducted according to the type of activity, the reproducibility was highest for occupational activity (r = 0.98) and lowest for sports/exercise (r = 0.89).

Discussion

The analysis showed no significant differences between the results of both studies, which indicates a low intra-subject variability and high reproducibility of the obtained results. The studies of repeatability and accuracy of the PPAQ conducted by the authors of the questionnaire showed that the intra-class correlation coefficients used to measure reproducibility of the PPAQ were 0.78 for total activity, 0.82 for moderate activity, 0.81 for vigorous activity, and ranged from 0.83 for sports/exercise to 0.93 for occupational activity [17]. Spearman correlations between the PPAQ and three published cutoff points used to classify actigraph data ranged from 0.08 to 0.43 for total activity, 0.25 to 0.34 for vigorous activity, 0.20 to 0.49 for moderate activity, and 0.08 to 0.22 for light-intensity activity. The high usefulness of the questionnaire for the assessment of physical activity of pregnant women has been confirmed in studies using it in many other countries [12–15, 20, 21]. Validation of PPAQ conducted by Chinese researchers demonstrated a very high reproducibility of 0.944, while the correlation coefficient between the results obtained on the basis of the questionnaire and the results of activity measurement using pedometer was r = 0.768 [14, 15], which showed that the PPAQ also allows for a reliable assessment of the activity of pregnant women with obesity and can be used in the assessment of adherence to the recommendations for physical activity during pregnancy as well as in the studies aimed at analysing the effectiveness of various intervention programs. Correlation between data obtained from the PPAQ and data from the measurement of activity using an accelerometer confirmed a moderate but acceptable accuracy of the questionnaire in a group of obese pregnant women.
This study, however, was subject to several limitations. Occupational activity and household/caregiving activities are quite similar in different seasons; however, sports/exercise activities may exhibit seasonal differences. Although each woman was studied in one season, the studies were conducted in the period from June to February. Moreover, the studied group was not representative of the general population. The analysis, however, confirmed the high reproducibility of results obtained using the questionnaire assessed. In the authors’ opinion, the PPAQ can be used to determine the lower and upper levels of rigor (intensity, duration, frequency) for activity during pregnancy, and to identify the specific parameters that characterise both threshold and dose response effects for investigations of physical activity and foetal and maternal outcomes [17]. The usefulness of the questionnaire for the assessment of physical activity in pregnant women should be emphasised especially in relation to the great need for further studies on the impact of physical activity and sedentary behaviour of pregnant women on the risk of adverse health effects for infants and mothers in their later life [1].

Conclusions

High reproducibility of results obtained using PPAQ questionnaire was found. This allows the assessed questionnaire to be considered as an accurate measurement tool that can be a source of reliable information about physical activity in pregnant women.

Conflict of interest

The authors declare no conflict of interest.

References

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Address for correspondence:

Grzegorz Król
Department of the Prevention of Alimentary
Tract Diseases
Institute of Nursing and Obstetrics
Faculty of Medicine and Health Science
Jan Kochanowski University
al. IX Wieków Kielc 19, 25-317 Kielce, Poland
Phone: +48 510 447 299
E-mail: g.krol@op.pl