Yokely & Glenwick (key study) - improving adherence using community interventions

context

Behavioural psychology has been used to modify people's behaviours in society in relation to many different areas such as nutrition, seat belt wearing and smoking. Immunisation uptake at that time was low for many preventable diseases such as polio, whooping cough, tetanus and rubella. This led to the deaths of millions of children across the world. Yokley and Glenwick (1984) reported 10,000 cases of preventable diseases in the USA in 1982.

aim

To evaluate the impact of four conditions for motivating parents to have their children immunised.

sample

The target population was children under the age of five who needed one or more inoculations for diphtheria, tetanus, whooping cough, polio, measles, mumps or rubella.

2101 preschool children were chosen from a register held at a public health clinic in a Midwestern city in the USA.

Of these, 1133 were found to be immune deficient and needing at least one inoculation.

Due to attrition the final sample consisted of 715 children. 50% male, 50% female. 64% white.

controls

Field experiment

Longitudinal design

Naturalistic setting

To avoid confounding variables, parents with two or more immune deficient pre-school aged children were allocated to conditions as a family to avoid the children receiving conflicting conditions.

controls - IV's

Random allocation of participants to the four different conditions (IV's):

1) Mailed out general prompt:

-- "Dear parent: Unless your doctor decided differently your child needs X doses of X vaccines at X ages. If your child is behind in any of them... I urge you to make an appointment to get your child caught up".

2) Mailed out specific prompt:

-- "To the parents of (child's name), our records show that it is time for... to receive the following shot(s): ... (specific list provided)... Shots may be obtained FREE of charge at the ... (Specific clinic location, dates, times)."

3) Mailed out specific prompt plus extended clinic hours:

-- This included the specific prompt above, plus: "ATTENTION: FOR YOUR CONVENIENCE, TWO SPECIAL OFF HOURS CLINICS ARE BEING HELD AT THE (clinic name) CLINIC (clinic address). Just sign all of your children in at the clinic and you may go out for the evening or day while we take care of them FREE of charge. Hope to see you there!". They were told this included drinks, movies and snacks.

4) Mailed out specific prompt plus monetary incentive:

-- "ATTENTION: IN AN EFFORT TO GET PARENTS TO HAVE THEIR CHILDREN IMMUNISED AGAINST CHILDHOOD DISEASES, THE AKRON HEALTH DEPARTMENT WITH SUPPORT FROM B.F. GOODRICH IS GIVING AWAY $175.00 IN CASH PRIZES TO PARENTS WHO TURN IN THE TICKET ATTACHED TO THIS PAGE". Parents were told that there would be three prizes of $100, $50, $25 and in order to be eligible for the lottery, parents had to bring their children to the clinic for immunisation and whilst there, tear off their ticket stub which had been mailed to them and put it in the clinic's lottery box.

controls - control groups and DV's

There were two control groups:

a) Contact control group: Received a telephone call asking about immunisation history of the child and for general demographic information, but no specific prompt was given to have their child immunised.

b) No contact control group: Received no contact during the study.

DV's included:

1) The number of children receiving one or more immunisations at the clinic.

2) The number of target children attending the clinic (for any reason).

3) The total number of immunisations received by the target children.

apparatus

Data was collected by measuring the number of attendees to the clinics for immunisations

method

Research record cards were created for the participants by the five undergraduate uni students who worked as research assistants for the study.

The record cards were created as the medical records were not allowed to be removed from the medical centre. Only information directly relevant to the study was used.

One of the four different prompts was mailed out to participants.

Parents were unable to give consent because they were not aware that the study was taking place.

Prompts were mailed out with a postage-paid postcard (addressed to the Health Department) so that each child's health clinic records could be updated if their child had already received the immunisation.

After two months, the lottery was drawn for the money-incentive group and prizes were delivered directly to the winners' homes.

A further follow up took place after three months. This means participants were followed up at 2 weeks, 2 months and 3 months.

results

Through each of the follow up periods, the effectiveness of the four interventions remained in the same order which was 4, 3, 2, and 1.

The monetary incentive was significantly more effective when compared to the no contact control group on all measures, and the contact control group on most measures.

After 2 weeks, the % increases in immunisations given were:

-- General = 4.8%

-- Specific = 8%

-- Specific + extended hours = 20.7%

-- Specific + monetary incentive = 28.6%

After 2 months, the % increases in immunisations given were:

-- General = 4.4%

-- Specific = 19.7%

-- Specific + extended hours = 29.9%

-- Specific + monetary incentive = 34.4%

After 3 months, the % increases in immunisations given were:

-- General = 9.6%

-- Specific = 24.5%

-- Specific + extended hours = 29.4%

-- Specific + monetary incentive = 31.6%

conclusions

Using behavioural incentives to motivate parents to have their children immunised is effective.

A single general prompt is not enough to motivate parents to immunise their children. Although the specific prompt did show a significant percentage increase in immunisations in the first and second follow ups (at two and three months).

strength - validity

A strength of this study is that participants were randomly assigned to conditions. Random assignment should mean that participant variables such as personality of the parents will not bias results. This means that researchers can state that having the monetary incentive with the specific prompt did cause more parents to inoculate their children, increasing the validity of the results.

strength - reliability

Another strength of the research is that it followed standardised procedures such as the same prompts within groups. This means that it had good reliability. It also means that the research can be replicated. This is important because replication of research demonstrates that the results were not due to chance making the research more reliable.

Weakness - generalisability

A weakness is that the results may not generalise to other parts of the USA or to other countries because parents from different socioeconomic backgrounds or different cultures may not be motivated in the same way. For example, there may be places where there is a great deal of mistrust in immunisations and a monetary reward may not be sufficient to persuade parents to get their child vaccinated.

weakness - ethical

An ethical weakness of the research is that parents did not consent to take part. They were unaware that they were participants and that their behaviour was being manipulated. In addition, there may be questions whether it is ethically correct to encourage one group with money in order to get their children immunised.

strength - ethical

A strength of the research is that following the data collection, both control groups received the specific prompt letter by post ensuring that the parents of children in these groups were also reminded that their children required further immunisations.

I&D - use of children in research

Although Yokley and Glenwick used children in their research, their focus was actually on the behaviour of their parents (influencing vaccination and what interventions were most likely to increase the parents' likelihood of getting their children vaccinated). However, even though the focus was on the parents, it was important that they considered the children when designing the study as their interventions could have potentially negatively impacted on vaccine uptake, such as being in the control condition. However, Yokley and Glenwick ensured that the control groups received a follow-up letter reminding parents to vaccinate their children after the study was complete, ensuring that no group was disadvantaged.