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Chapter 6: Materials and Methods

6.1 ETHICAL APPROVAL

This study was approved by the Institutional Ethics Committee (No.

IEC/KMC/02/2006-2007), Kasturba Medical College, Mangalore; and meets

the ethical principles guidelines as per the Declaration of Helsinki.

6.2 RESEARCH METHODOLOGY

i. Study Setting

The study setting for this study was the individual homes of the

infants/children’s parents within limits of Mangalore City Corporation.

ii. Study Design

Longitudinal method to study motor development is important because of

individual differences in the attainment of motor skills. 106 Since motor

behaviors is a process of continuous organisation and reorganisation 106

which can be understood well through the serial assessments.

So, this study has applied correlative research design 45 (where outcomes

were related to previously measured antecedents) in order to track intra-

individual change and inter-individual differences, as the same functions

were measured at different ages.

iii. Study Duration

October 2005 to April 2010.

iv. Study Subjects

Normal infants without any post-natal or neonatal events and residing

within limits of Mangalore City Corporation as per the following inclusion

and exclusion criteria:

47

a. Inclusion Criteria

1. Only Normal delivery-term baby with no natal or post natal

complications

2. Birth weight ≥ 2.5kg.

3. Baby with normal medical and nutritional status.

4. Baby performing as ‘Normal’ or ‘Transient’ on the Infant Neonatal

International Battery (INFANIB).30

b. Exclusion Criteria

1. Low birth weight (<2.5 kg.)

2. Premature infants

3. Infants with specific pathologies i.e. Mental Retardation, Down’s

syndrome, Microcephaly, Cerebral Palsy, Orthopedically and

neurologically challenged.

4. If an infant suffers serious medical problems during the study,

which may have long term deleterious effect on growth &

development, will be excluded from the study.

5. Any child, who misses more than two consecutive session of

assessment, will be excluded from the study.

v. Sampling

Purposive sampling procedure was used for this study because major

requirements for the three years follow-up necessitated smooth

implementation of infant’s periodical follow up. Therefore infants were

recruited in this study on following basis to avoid un-eventful dropout from

future follow up assessments;

a. Infant’s parents must be a resident of Mangalore City and have

houses within limits of Mangalore City Corporation,

b. Infant’s parents must be residing within limits of Mangalore City

Corporation for the next three years or more.

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Study Plate: 1 Mangalore City Corporation Map (Study Location)

49

vi. Sample Size Estimation

(Zα + Zβ)2 * [1+(m-1) ρ ] σ2 n = d2

Where,

Zα = Critical Value at 5% level of significance (1.96) 165

Zβ = Critical Value at 80% power (0.87) 165

m = Number of repeated time points/follow up (10)

d = Minimum anticipated difference in the total motor score

from the base line to 36 months (1.6) 26

σ = Standard Deviation (3)

ρ = Interclass correlation coefficient (0.3) [anticipated]

(1.96 + 0.87)2 * [1+(10-1) * 0.3 ] * (3)2

n = (1.6)2

n = 36.81 ≈ 37

Anticipating 15% dropout, thus

n= (1 + 15/100) * 37 = 43 approximately.

42 infants/children had successfully completed the due process of birth (1-

2M) to 36 months longitudinal periodical follow-up assessments till the

completion of data analysis process. The average dropout rate in this

study was 19.23 %.

Note: Based on (Kalverboer,1993) apprehension, regarding the subject’s

attrition in longitudinal research design from one age to another age1 in

the initial stages of recruitment process, we had maintained strict

adherence with the above guidelines to keep the attrition rate low. Our

anticipated dropout rate was 10-15%, but actually it became 19.23% (n=

10). We had loss of follow up (at different age points) for 4 infants within

12 months of infant’s recruitment because of parents migration to a

50

different city or country, 2 infants parents had refused for further follow-up

visits and 4 infants had developed medical complications (e.g.

convulsions, metabolic disorders, prolonged illness etc). These infants (n=

10) were excluded from the overall data analysis procedure.

vii. Research Materials

Materials used in this study are

a) Peabody Developmental Motor Scale-Second Edition (PDMS-2)- Test

Kit and other essential testing items (not provided with the kit) for test

administration,

b) Peabody Developmental Motor Scale-Second Edition (PDMS-2)

Examiner’s Record Booklet to enter the motor assessment findings at

specific age periods,

c) Peabody Developmental Motor Scale-Second Edition (PDMS-2)

Summary Score Form for the documentation of subtests and quotients

at specific chronological ages,

d) Peabody Developmental Motor Scale-Second Edition (PDMS-2)

Software Scoring and Report System to obtain the subtest’s and

quotient’s scores,

e) Peabody Developmental Motor Scale-Second Edition (PDMS-2)

Examiner’s manual to interpret and analyse the study findings,

f) PDMS-2 sample size for each normative age group (appendix A;

which is not provided in the manual table A.1 through A.37) from Pro-

Ed, Inc. Austin, TX.

Note 1: Permission to use PDMS-2 scale in this study was obtained from Technical Advisor, Test Development Department,

PRO-ED, Inc. Austin, TX 78757 through an E-mail communication from tmaddox@proedinc.com dated January 14th 2005.

Note 2: Sample size of the PDMS-2 at each normative age group was obtained from Research Associate, PRO-ED, Inc. Austin,

TX 78757 through an E-mail communication from lrogers@proedinc.com dated May 21st 2010.

Study Plate: 2 Peabody Developmental Motor Scale

Kit, Examiner’s Record Booklet, Summary Score Form, Software, Examiner’s

Manual, Guide to Test Administrations and Motor Activities Program.

Study Plate: 2 Peabody Developmental Motor Scale-Second Edition (PDMS

Kit, Examiner’s Record Booklet, Summary Score Form, Software, Examiner’s

Manual, Guide to Test Administrations and Motor Activities Program.

51

Second Edition (PDMS-2)- Test

Kit, Examiner’s Record Booklet, Summary Score Form, Software, Examiner’s

Manual, Guide to Test Administrations and Motor Activities Program.

52

viii. Data Collection Procedure

Following flow chart gives an outline about the infant’s recruitment process

used in this study for the purpose of data collection.

A signed typed notice detailing about newborns recruitment for the analysis of motor

assessment from Birth (1-2 months) to 36 months was displayed on “Well Baby Clinics”

notice boards. Interested parents were requested to register their infant’s name/home

address/contact number with the respective pediatric unit.

Registered infant’s parents were communicated by the tester to get the location of their

residences and requested permission to visit their home. During first home visit tester

explained to parents about the study. Then parent’s oral agreement for their infant’s

participation in the study was obtained.

Infant's demographic and neonatal details verified from infant’s ‘Birth Record’ according

to the proposed inclusion and exclusion criteria and first assessment home visit was

confirmed.

During first assessment home visit parent's written consent for their infant’s participation

in the study was obtained prior to the administration of PDMS-2 scale.

Periodical assessment of Infants/children on PDMS-2 scale was conducted through home

visits by the tester according to the pre-confirmed scheduled date and time as per the

study design. The same process is followed up till 36 months of age.

After obtaining permission from the institutional heads of Government Wenlock District

Hospital and Kasturba Medical College, Mangalore; “Well Baby Clinics” of department of

pediatrics was approached for permission to recruit infants for the proposed study.

53

Through this process a total of 52 infants were recruited in the study, but

only 42 completed the full 36 months follow up of motor developmental

study from birth (1-2 months) on PDMS-2 instrument.

The above flow chart shows the actual sample statistics and the number

of subjects who completed the full 36 months follow up of motor

development study from birth (1-2 months) on the PDMS-2 scale.

The above process was followed till the required numbers of subjects

were enrolled in the study. During the first home visit (once state of

congenial atmosphere gets established, important because of stranger’s

visit to a newborn’s home), parents were explained about the study in

their own language of understanding. Then through newborn’s birth

record, infant’s eligibility for participation in the study was ascertained.

Contents of the PDMS-2 testing kit and demonstration of motor

development analysis procedure was made before the family members.

Following this, parents were requested by the investigator to ask the

questions to ensure that no doubts are left unexplained.

Then, after obtaining the confirmation of parent’s willingness regarding

their infants participation in the study, investigator took appointment from

the respective parents as per their convenience and newborn’s

comfortability and the first assessment home visit was conducted. During

Total Infants Recruited for the Study

n=52

Infants/children completed the full 36M

of motor development follow-up

analysis

n=42

Infants/children dropped from the study at various chronological ages

n=10

54

the first assessment home visit, infant’s demographic data (see Appendix:

XII) and written informed consent (see Appendix: XIII) was obtained. Each

parent was also given PDMS-2 record booklet for their references.

ix. Study Process

Infants were selected on the basis of an optimal pregnancy and delivery

status and an uneventful neonatal or post-natal course. Throughout the

follow-up, diseases were accepted only if there was clear evidence that

nervous system was not involved. All infants were belonging to families of

variable socio-economic class according to the ‘New scale for measuring

Socio-economic status of family’. 166 All parents were young adults, where

father’s & mother’s mean age was 34.64 ±4.61 & 28.11±3.74 respectively.

(This helped us to avoid the differences in rearing attitudes during infancy.

However, it was not possible to standardise the birth rank order of the

selected sample, but all the families were small and number of children

not exceeding two).

Infants were assessed through home visits preferably in late morning or

late afternoon or early evening. Each assessment session lasted for about

2 hours. The first 15 minutes to 30 minutes usually given with the purpose

of infant’s adjusting to the examiner’s presence. Tests were administered,

when infants were awake, cooperative and anticipating according to the

PDMS-2 test administration instructions. At each scheduled assessments,

investigator had ensured that mother is present during the testing period.

Involvement of both parents was encouraged to facilitate infants/children’s

motivation in test items. Each infant’s attention was drawn towards the

related test activities of the PDMS-2 items through demonstration by the

investigator to the infant in mother’s presence (or either of the parents)

and then mother calling infant’s name and facilitating him/her in their own

language to perform the test activities. Test items were presented in

55

gradual and random order on subtests of gross and fine motor skills in

order to maintain infant/child’s mood, interest and motivation. Data were

recorded in the PDMS-2 examiner record booklet.

These assessments usually were conducted on Sundays or holidays of

the week. In the second half of the first year particularly, it become

increasingly important to spend much time and energy on creating right

mood and positive behavioral state among infants.

x. Data Collection Frequency

Data collection frequency used in this study was as follows: 23, 36, 111

(a) For Birth to 11 months age duration, test administrations were

performed at every 3- month’s interval from the date of infant’s

recruitment in the study.

(b) For 12 months to 36 months age duration, test administrations were

performed at every 6- month’s interval according to the infant’s birth

date.

Note: Since all infants were not recruited at one time point (some were

recruited at 1 months of age [n= 18], while some at 2 months of age [n= 24]),

therefore in the age range of birth to 11 months, there were two different

corresponding age points of test assessment. But from 12 months, all age

points become single age point of assessment [n= 42] throughout the

remaining study period till the age of 36 months.

To ensure the smooth conduct of follow-up assessment program,

following guidelines were adopted for this study:

a) A permissible duration of + 15 days for birth to 12 months (0 – 12) age

group infants and +30 days for 1 year to 3 years (1 – 3) age group

infants/children were provisioned in the study methodology for the

assessment schedule. This was done with the sole purpose that

56

infant’s routine sickness and family’s social obligations must not come

in the way of longitudinal follow-up assessment plan.

b) Each assessment was made when infant/children were in alert and

active state of mood to get the best motor response. Assessments

were postponed to the next most appropriate date and time in

consultation with parents, when investigator noticed that child was

tired or was sleepy. It was ensured that when infant/child had common

cough and cold or fever, assessments were postponed for a week or

so.

xi. Additional Observations:

During the process of test administration, we also observed following

related information, which were not used for data analysis purposes:

Infants’ rearing attitude by parents, Infant’s interest in the tasks, approach

to the understanding of instructions, problem solving, directionality in

transferring materials (i.e. Lt to Rt or Rt to Lt), use of self- corrections,

preferred hand use in grasping, drawing, cutting, throwing, smoothness,

agility and coordination in execution of motor movements, overflow activity

prior to, during, or after performing an item and infant’s feeling about the

individual performances.

6.3 STATISTICAL ANALYSIS

Descriptive statistics (mean, standard deviation, minimum, maximum and

coefficient of variation) for PDMS-2 subtests raw scores and quotients scores were

used to summarize the data at all chronological age points of assessments.

Generalized estimating equation (GEE) with dunnet post hoc test was used to

compare the profiles of raw scores (to assess motor development rate) across the

chronological ages for subtests and quotients.

57

For each subtests of the PDMS-2, normative data was presented based on

the raw scores. Initially ‘z’-scores was computed and the same were transformed to

‘T’-scores (with mean of 10 and standard deviation of 3) for subtests and (with mean

of 100 and standard deviation of 15) for quotients. Subsequently corresponding ‘T’-

scores were transformed to ratings (as defined in the PDMS-2 examiners manual

table 4.2) for subtests and quotients scores as per the table 4.3. 26

Table: 1 Guide to Interpret PDMS-2 Subtests and Quotient Scores

Guide to Interpret PDMS-2 Subtest Standard

Scores (Table 4.2) 26

Guide to Interpret PDMS-2 Quotient Scores

(Table 4.3) 26

Standard Scores Description Description Quotient Score

≥15 Superior Superior ≥121

8-14 Average/Above Average Average/Above Average 90-120

≤7 Below Average Below Average ≤89

Source: PDMS-2 Examiner’s Manual 26

2-sample Kolmogorov-Smirnov test was used to compare percentile rank

distribution of study sample for the subtests (Reflex, Stationary, Locomotion, Object

Manipulation, Grasping and Visual- Motor Integration); and quotients (Gross Motor,

Fine Motor and Total Motor Quotients).

Bland-Altman Plot and Scatter Plot were used to compare agreement

between chronological ages and age equivalents. 167

In this study Bland-Altman Plot is used to see agreement between the two

measurements. It is plotted against the difference of two measurements (or mean of

difference). There will be a centre line at or mean of difference and two threshold

lines (above and below the centre line). If any point falls beyond upper or lower

threshold then it indicates lack of agreement between the two measurements.

Another way to look in to the agreement between the two measurements is by

scatter plot diagram. In this, a diagonal line passes through the ‘0’. If there is a

perfect agreement, then all points should go along the reference diagonal line.

SPSS version 15.0 was used for data analysis. A p value of <0.05 was

considered to be statistically significant.