A CEPTACIÓN DEL S ISTEMA

6.1.1 Recruitment and size of sample

The Ethics Approval committee stipulated that the recruitment process required

potential eligible participants to be contacted by the health visitor in the first instance, for invitation into the study. This could not be done by the primary researcher. The action of telephoning all the recipients of invitation letters required a considerable amount of time, additional to the health visitor’s usual workload. Therefore, despite the health visitor’s best efforts and commitment to the project, the number of

uncontactables may have been lower if the primary researcher had been able to spend time trying phone numbers on repeat occasions at different times of the day, and different days of the week.

The recruitment process, the small population size available for invitation to participate in the study and the pilot nature of the study, prevented large numbers being engaged in the study. Other methods of recruitment were explored, including recruitment at playgroups and health visitor-led baby clinics. However, there were very little eligible participants attending these that had not already been invited by letter. The small sample size means that statistical tests may have low power to detect any statistically significant effects, particularly when analysing subgroups of the participants. However, the study was only ever intended to pilot the dietary assessment tool and examine its practical utility for use in healthcare interventions or studies. The distribution of participants across socio—economic groups was more important than number of

participants, in examining whether the diet diary was acceptable for use and completed to a high standard by all groups.

Ethnic minority groups were under-represented in the sample (partly due to the locality of the study). Also, it has to be considered that potential participants with difficulty reading/writing English may have been less likely to participate, due to not

understanding the invitation letter and information sheet, and perceived problems with completing the diet diary. Further assessment would be needed to examine the

6.1.2 Time of year

The period of participant engagement was from May to September, and this time of year may be associated with more holidays and days away from home, therefore greater difficulty contacting participants, and possibly more refusers, due to these summertime activities.

From another perspective, there is a consideration that diet in the summer may be different than winter months. Although the British climate does not have dramatic seasonal variations, warm summer days may result in higher recording of foods such as ice-cream, ice lollies, jelly and refreshing drinks than a diary completed in the winter.

6.1.3 Diet diaries

As discussed in section 2.9.2.3, as with all dietary assessment tools, there are limitations to diet diaries, which are difficult to overcome. However, it was decided that with the rapid development of an infant’s diet over a short period of time, the other methods discussed would not capture accurate detailed information for this age group. Diet diaries rely on the participant to complete independently and may be considered burdensome in some cases, and so the results are only as valid as the participant’s ownership and commitment to the research. There is the potential for participants to over-report or under-report dietary behaviour(Stone et al, 2003). With young children, where small quantities are being examined, misreporting could have considerable effect on the nutrient intake calculated. There are potential difficulties with estimating portion sizes/quantities, the amount of food wasted or left over, and having different carers completing the diary (Higgins et al, 2009).

It has to be accepted as a limitation that there may be the potential of participants to report behaviour which is considered socially desirable, particularly in health research studies. This could be either by misreporting behaviour on the diary, or changing to more acceptable behaviours during the diary period. From the feedback comments collected, it may be considered that this may be less likely the case for parents recording the diet of their young children rather than their own diet, as they wish to ensure that they are feeding correctly and receive any advice to aid this.

For the complex nutritional analysis, a senior nutritionist had to make some estimations of ingredient quantity for some home-cooked meals. This was because the participants had given the quantity eaten of the whole meal, rather than individual constituents, which would have been estimation in itself of the amount of each constituent on the

participant’s plate. This assumption of the ratio of ingredients within a meal (for example, within spaghetti bolognaise sauce) was deemed acceptable and likely to have very little effect on the results expected. The calculation of nutrients could create under/over-estimation of intake, when quantities were not clearly stated in the diary. Also, it was not possible to estimate the amount of breastmilk consumed, despite recording of the length of feeds, due to individual factors.

6.1.4 Medicines

It is a limitation of the study that the role of regular medicine use on dental health was not explored. Nineteen percent of participants reported giving regular medicines and during the diary period, 14% recorded giving medicine. The quantity of sugar within these medicines and the regularity of their use could be of concern for increasing the risk of early childhood caries. This requires further investigation, which was not explored within this study.