Methodology of Research - Assignment Example

Chapter 2 Methodology 2.1 Background This study is a retrospective analysis of the ISWT in phase III CR. Reports used were gathered from an extensive data set that formed a part of the Have a Heart (HaH) Paisley, Phase I, a project financed by the government and carried out at the Royal Alexandra Hospital Paisley, in Scotland. The project was conducted from May 2003 to April 2004. The main objective of the HaH Paisley project was to examine the efficacy and competence of menu based CR. Primarily, the data used assessed variables such as nutrition, education, psychology inputs and patient health risk factors encompassing smoking, cholesterol, weight, blood pressure and physical activities. The patients included in the HaH Paisley project participated voluntarily and therefore, they signed up consent forms which permitted their data stored and evaluated. 2.2 Functional Capacity Assessment Participants included in the CR have to undergo an examination using an ISWT conducted by a physiotherapist or an exercise physiologist. In the United Kingdom, this walking test is the primary test used in CR. The walking test is externally paced and uses a pre recorded audio signal. The test is fashioned in such a way to stress the participant into an individual symptom limited maximum, by making the participant walk along a ten meter flat surface course and making a u-turn around a cone at every end. According to (Singh 1992), the walking test encompasses twelve levels with each level being one minute long and increasing in pace. The detailed information on the 12 levels of the walking test, the distance in meters and the velocity in mph and kph of the whole test is illustrated fully in Appendix 2. For this study, the ISWT will be carried out in compliance to the guidelines charted in SIGN 57 (2002) with the exemption of documentation of the Heart Rate (HR) at the end of each of the twelve levels where only two HRs will be recorded. That is, one HR reading will be performed pre-test and one HR reading at the end of the test using a polar Heart Rate -monitor in order to acquire accurate readings. Moreover, another exception is made where no practice tests will be done owing to time limitations and available funds for remunerating the physiotherapy personnel. The tests will be carried out within one gymnasium and at similar intervals before and after the thirteen week course of the menu based CR. Subsequently, test data comprising of MDW- Maximum distance walked during the test, RPE- peak rate of perceived exertion and MHR- maximum heart rate from ISWT, will be collected and recorded in the database 2.3 Ethical Consideration Since exercises and cardiovascular diseases present certain level of risks to patients, all the exercise sessions to be carried out will be facilitated by a fully and suitably qualified physiotherapist and an exercise physiologist and supervised by a nurse who is effectively equipped with advanced or intermediate life support skills, knowledge and proficiency. To ensure safety and to further limit participants’ risks, participants will not only have to answer specific questions to ascertain their credibility as suitable candidates for the test but also, their blood pressure will be monitored before the test begins. Appendix 3 illustrates the pre –test checklist used as criteria to screen suitable participants. 2.4 HaH Cardiac Rehabilitation Exercise Class During the HaH Paisley project, the CR exercise program entailed an hour track or gym based exercise session performed twice a week and an optional third day a week similar exercise session done at home. The CR exercise program at HaH Paisley project encompassed a Track-based exercise session; The session is divided into four sections which comprises of a fifteen minute warm up involving the participants doing stretches, twenty minute of track stations with ten exercises with three varied levels, ten minutes for cooling down and ten minutes spent in participants relaxing or undergoing resistance training. Gym based exercise session; the exercise session is in five sections comprising of a ten minute warm up riding the bike, five minutes of participants doing stretches, twenty five minute of cardiovascular exercises where participants use treadmills, gym bikes and Concept II rowing machines, ten minute resistance training session and ten minutes of cooling down. 2.5 Participating Patients for the Retrospective Study The initial population sample of 234 participants included in this study coupled with their full ISWT details were established from the data base developed during HaH Paisley project. Conclusively, a total of 184 participants qualified for final analysis having gone a screening test. The population sample included 61% male with an average age of 64 years (+/- 8) and 39% females with an average age of 66 years (+/-8) which are equivalent to 112 male and 72 females respectively. The ethics approval was acquired through the (HaH) Paisley; Phase I. Appendix 4 illustrates the Ethics Approval letter. 2.6 Study Design and Dataset for the Retrospective Study The main reason for using a retrospective study design for this study is the ease with which the researcher will be able to access large capacity of data gathered during the 13 week HaH Paisley, Phase I project. Importantly, the data set to be used in the retrospective analysis of the ISWT in phase III CR will be collected from participants, who have already finished the ISWT before and after the menu-based CR, post cardiac event conducted at the Royal Alexandra Hospital in Paisley, Scotland. Identification of suitable candidates to participate in this retrospective analysis will be done by searching for participants with full data set as recorded in HaH Paisley database and a search for suitable participants in archived physiotherapy profiles, which are specifically handwritten by participants. The physiotherapy reports of the results from ISWT will be verified by hand and they will undergo a stringent exclusion procedure that entails a manual documentation of the HR, commencement or changing the beta blocker medication dose during analysis and abolition of ISWT by the instructor among other principles not complied to as outlined in 57 guideline (2002), apart from the exceptions earlier indicated. 2.6.1 Inclusion Criteria The participants to be included in the analysis will need to satisfy the following criteria, All those referred to CR at the Royal Alexandra Hospital, Paisley due to a step change which may be an acute cardiovascular occurrence or deteriorating CHD condition Patients diagnosed with CABG - Coronary Artery Bypass Graft, MI -Myocardial Infarction, Congestive Heart Failure, Acute Coronary Syndrome, New Diagnosis of Angina/ deteriorating Onset of Angina, Valve Replacement and Percutaneous Transluminal Coronary Angioplasty Participants who did an ISWT prior to and after the thirteen week CR course ISWT records that have information on resting and peak heart rates, peak RPE, Medication, MDW in meters and reasons offered for ending the test. 2.6.2 Exclusion Criteria For the retrospective analysis, participants who fail to meet some of the standards such as manual recording of heart rates and failure to record peak HR during the test will be eliminated. Although 196 participants were initially identified as suitable candidates for analysis during the search using patient handwritten physiotherapy profiles, only 184 of them qualified when the exclusion criteria was applied. Appendix 5 gives a detailed description on the various reasons for exclusion. 2.7 Data Data on readings prior to and after analysis will be gathered for every participant during the ISWT and a new data set will be developed using SPSS (Statistical Package for Social Sciences software program) that contains information on Maximum heart rate, maximum rate of perceived exertion and the maximum distance walked. Among other calculations integrated for the study includes the speed in meters per minute and the walking speed index- WSI. In order to enhance accuracy of the analysis in relation to speed and level attained on the ISWT, participants will be granted a new level in velocity if only they finished thirty second of the stage. The cut off points for each level for assignments of speed are illustrated in Table 1 Level 1 = 20 meters Level 2 = 50 meters Level 3 = 100metres Level 4 = 150metres Level 5 = 220metres Level 6 = 290metres Level 7 = 380metres Level 8 = 470metres Level 9 = 580metres Level 10=690metres Level 11=820metres Level 12=950metre Table 1 The calculations would be changed only to compute the walking speed index. This means dividing the heart rate by speed in minutes per minute based on the levels illustrated in Table 1. For the overall analysis, no additional alterations would be made on the true Maximum distance walked, heart rate or RPE. 2.8 Walking Speed Index (WSI) The walking speed index is primarily developed to help compare the peak heart rate after ISWT. In this study, analysis on all HRs at increasing workloads will not be obtained since only two HRs will be acquired during the test, that is, prior to and after the test. This analysis aims to examine peak HR to establish whether it altered significantly after the 13 week CR course. As (McArdle et al 2007) notes, when a participant shows enhanced physiological fitness, their HR therefore would reduce at any given workload after rehabilitation. The walking speed index used will be based on physiological cost index established by MacGregor in 1979, which was recommended as an option to VO2 calculations in locomotive studies on different disabled groups like cerebral palsy owing to the complexity of equipments needed for gas air assessment. The walking speed index functions on the principle of linear correlations between heart rate, VO2 and work rates, where shifts in HR response is a suitable alternative to changes in VO2 as indicated by (McArdle et al 2007). WSI is acquired by dividing the peak HR by speed in meters per minute to generate an index rating. Importantly, the index is anticipated to be lower after rehabilitation if the HR would have altered significantly for any given WSI hence, lower work rate and VO2 as illustrated in Appendix 3. 2.9 Data Analysis As earlier indicated, only 184 participants will qualifies for the final test when the exclusion criterion is applied. The SPSS software program will be utilized for carrying out the tests. Among variables to be analyzed are namely the Maximum distance walked, heart rates in bpm- beats per minute, RPE of s-20 scales and walking speed index in bpm. The retrospective study design will be repeated calculations with ratio level data and thus, develop the parametric paired t test. When the participants are equivalent to more than a hundred, the Kolmogorov-Smirnov test will be utilized to check for normality of distribution. Since there is a probability that the distribution may fail the assumption of normality (p=>0.05), a non- parametric test, the Wilcoxan Sign Rank test, will be used as an alternative test. The level of significance will be set at (p=0.05) with the summary data (SD) being expressed as average SD owing to the level of data drawn in. To assess if participants enhance their physiological fitness, the considerable difference will be analyzed from analysis of data obtained. This will be achieved by evaluating the mean rise in Maximum distance walked and the mean decrease in WSI- which illustrates an increase in physical fitness, to assess if they concur. This means that a 30% increase in distance walked should be accompanied by a 30% average decrease in WSI. 2.10. Heart Rate Recovery and ISWT The heart rate recovery refers to the rate the heart rate decreases to resting levels from maximal and sub maximal exercises. It is established as an autonomous determinant of major causes of deaths in fit adults (7, 8, 9) ailing from CVD (10, 11) and diabetes (12). In addition, it is a vital accompaniment to health checks and physical evaluations of patients (13). It takes approximately one hour of HR recovery to resting levels following light to moderate exercises (14), estimated four hours following prolonged aerobic exercises (15) and approximately 24 hours after intense exercises (16). HR recovery to resting levels can sometimes rely on interface between factors such as intensity of exercise (14, 17), cardiac independent modulation and the degree of physical fitness as indicated by (18, 19, 20). In order to calculate the heart rate recovery, researchers have either computed constants of time by aligning heart rate decay information on varied statistical frameworks (21, 22-23) or measured the decline gradient or calculated the HR shift from peak exercise to two minutes of HRR (7, 10, 21). In healthy adults, a 15-20 bpm fall is observed within the first minute of HRR after the exercise (9, 24). Primarily, a heart rate decrease of lower than 12bpm in first minute post exercise is expected in active HRR (7) while post rigorous exercise test, an 18bpm in inert HRR during supine position indicates a high risk of death from cardiovascular for asymptomatic patients and cardiopaths (7, 9, 10). 2.1.1. Maximum Oxygen Consumption interrelation with HRR Maximum oxygen uptake entails the largest capacity of air one can breathe in and utilize throughout a rigorous exercise while engaging an extended fraction of sum muscle mass (56). The maximum oxygen consumption is the best determinant of cardiovascular fitness and exercise power and corresponds to the amount of oxygen circulated and consumed during cellular metabolism (1). Varied previous researches (19, 29) indicate that HRR is linked to VO2 max. Based on these researches, increased HRR is seen in athletes with high VO2max than non-athletes. In addition, variables such as exercise patterns, age and cardiac vagal exercises that impact VO2max are linked with HRR. Case in point is that maximum oxygen uptake (1, 57) and recovery (19) are conversely linked with age. Maximum oxygen uptake is effectively increased by physical work outs (1, 58-60) while untrained individuals have slower recovery compared to skilled athletes (19, 28-29). Utilizing a power spectral analysis on a study on thirty seven healthy participants following a bike exercise, Goldsmith et al (61) noted high maximum oxygen intake for participants with high vagal activity. In a different study on healthy males after a bike exercise done by Tulppo et al (62) indicate during the exercise, there is a correlation between damage of vagal function and poor physical health. Importantly, vagal activity is the main cause for recovery (26, 63). 2.12. Importance of HRR The HRR plays a vital role in helping clinicians to accurately and effectively diagnose and give prognosis on ANS and observe cardiac functions. Use of HRR is not only easy but saves on time and resources especially during rehabilitation in cardiac situations. Since ANS abnormalities are associated with risk of fatality, intricate tools and check ups are needed to measure the abnormalities, which are hard to do. Therefore, using regular routine exercise check up, clinician uses the HRR for prognosis of patients at low risks and those at risk of dying. Equally, it generates a guide for exercise recommendation for exercise physiologists and thus helps assess the degree of physical fitness of a patient. Therefore, HRR is used to identify patients with low risks who have normal HRR, which helps the clinician in managing the condition predictably without the need for further check ups which might expose them to potentially risky procedures. Moreover, identifying patients at high risk of dying associated with autonomic imbalance, who have abnormal HRR. Research shows that HRR bnormalities can be modified using exercise training and pharmacological therapy. Chapter 3 Results 3.1 Basic demographic data This is a retrospective study that utilizes data gathered from 184 patients who participated in the (HaH) Paisley, Phase I project carried out to analyze CR at the Royal Alexandra Hospital, Paisley, Scotland from April 2003 to March 2004. The initial data base had 234 participants, 38 of whom were eliminated for lack of corresponding hand written profiles, which was mandatory for inclusion in the test. An additional twelve were eliminated on the basis of changes in dosage or inaccurate HRR records. As indicated in Chapter 2, the population sample were 61% male with an average age of 64 years (+/- 8) and 39% females with an average age of 66 years (+/-8) which are equivalent to 112 male and 72 females respectively with the difference in average age and gender being p=0.926. Most of the participants fell in 55-74 year bracket. Participants comprised of MI accounting for 34% of patients, 21% Ang, and 19% CAB G and 15% PTCA respectively. VR, ACS and CHF accounted for the remaining patients. 71% of the participants were on beta blocker drugs. 3.2 (ISWT) Results 3.2.1 Results by Levels As earlier mentioned, ISWT is made of twelve one minute levels. For instance, when level 5 shows 5 METS (Woolf-May et al 2008), 75% of participants record level 5 or exceed pre-rehabilitation as shown in figure 5 and 88% post rehabilitation as shown in figure 6. Only 1% of the participants attained the last level of the test (n=12) pre-rehabilitation while 7% attained post rehabilitation. An average level 7 and level 8 is acquired pre rehab and in post rehab respectively. During pre rehab, all patients acquire an average distance of 387m (95% CI 360m-414m) and an average of 492m (95% CI 460m-523m) post rehab. 3.2.2 Results by Age Groups During the test, participants aged 55-64 years walk further 453m pre rehab and 557m post rehab. Their distance is 4% to 68% post rehab more than the other age groups which is a 27% increase in distance obtained prior to and after the 13 week CR course. The age groups 75 years have the lowest mean distance when walking pre rehab which is 269m, +/- SD making the highest improvement of 88m post rehab, which is equivalent to 33% increase. The peak heart rate rises between 4% and 9% which is equivalent to 4bpm to 9bpm and an increase in RPE between 5% and 9% with the highest increase being noted in the 55-64 age groups. 3.2.3 Results by Diagnosis Based on findings through diagnosis, MI and ACS groups are combined as Myocardial Infarction (n=72) and PCI and CABG as Revascularization (n=62). Patients diagnosed with Angina (n=39) are taken care of as an individual category while the remaining groups of CHF and VR are excluded due to the fact the numbers were too small to generate details, ie. (n=9). The pre and post maximum distance walked for the MI category is 378m (+/-188) and 484m (+/-219) in that order as illustrated in figure 7, which is a substantial rise (p=0.0005) of 28%. The HR rises by 6 bpm (p=0.002) with a RPE increase between 12.14 (+/- 2.0) and 12.90 (+/- 2.5). The maximum distanced walked is enhanced by the Revascularization Group by a mean of 111m as illustrated in fig 7, which is major rise (p=0.0005) of 27%. The HR increases insignificantly from 106- 110 while RPE alters notably (p=0.014) between 12.16 (+/-1.8) and 13.18 (+/- 2.0). The mean maximum distance traveled for the Angina category is 96m further (p=0.0005) as illustrated in figure 7. There is a significant increase of HR by 6bpm (p=0.002) and insignificant change of RPE from 12.92- 13.19 3.2.4 Results by Gender The mean distance walked by male participants (n=122) is 440m, Level 8 pre rehab and 555m, level 9, post rehab. On the other hand, the distance walked by females is 303m, level 6 pre rehab, 45% lesser and a mean of 393m, level 7, 41% lesser post rehab. During the test, 17% of male attain level 10 or exceed pre rehab contrasting the 1% female participants. Be it as it may, female participants indicate a 30% average rise in percentage walked post rehab compared to 26% in male, with the peak HR for male is 112, 6% increase post rehabilitation and a rise of RPE from 12.6 (+/-SD 1.8) to 13.6 (+/-SD 2.0) and mean HR for female increasing 6bpm and a rise of RPE after the 13wk CR course between 11.8 (+/-SD 1.8) and 12.4 (+/- SD 2.1). 3.3 Analysis The ratio level data are the heart rates, maximum distance walked, walked speed index and RPE although the factors assessed over two time points do not pass the normality test for failure to generate results of p=>0.05 that makes the distribution abnormal, which necessitates the use of a non-parametric test, the Wilcoxan Signed Ranks test rather than a parametric one. A major level of p=0.0125 is set that encompasses a Bonferroni adjustment for the four factors (p=0.05*4). For the analysis, the results on all variables for all 184 patients are computed excluding the RPE carried out on 79% (145) of the category. As shown in table 3, the results indicate a major rise (p=0.0005), 105m (387m +/- 186m to 492m +/-216m) in MDW during pre and post rehab for all participants. Moreover, the peak HR substantially increases (p=0.0005) from 101 (+/- 22) bpm to 108 (+/- 25) bpm, a significant increase in RPE (p=0.0005) from 12 to 13 is noted and as illustrated in Tables 2 & 3, a major decrease is seen in the WSI (p=0.0005) from 1.25 (+/- 0.31) bpm to 1.15 (+/- 0.26) bpm. 3.3.1 Males and Females Upon calculation of gender disjointedly, a significant rise in MDW is seen (p=0.0005) from 303 (+/- 133) m to 393 (+/- 155) m, a major rise in HR (p=0.001) from 95 (+/- 18) bpm to 101 (+/- 22) bpm is also observed while the (p=0.001) from 1.32 bpm to 1.20 bpm of WSI illustrates a substantial decrease. In regards to male, the (p=0.0005) from 440 (+/-195) m to 555 (+/-227) m indicates a rise in MDW while the (p=0.0005) from 106 (+/-24) bpm to 112 (+/-26) bpm shows an extensive HR increase. However, a major decrease in WSI is observed (p=0.0005) from 1.21 bpm to 1.12 bpm as illustrated in Table 6&7. There is 115 (+/-129) m mean difference in distance post rehab for males and for females it is 89 (+/-78), which is an insignificant difference (p=0.145). 3.4 Maximum Distance Walked versus Physiological Fitness During maximum distance walked, the results for change in performance computed as a rise in percentage from base line to follow up show participants indicates a major mean increase of 27%. In order to establish the degree of change as a result of physiological benefits, it is compared with WSI, which demonstrate a physiological gain founded on a fall in HR at any given level. From the results, an 8% mean increase is noted in physiological change in fitness thus, the 19% remaining becomes the function of other variables like confidence, familiarization and movement efficiency (practice). When the genders were calculated disjointedly, parallel outcomes were observed. A 30% average rise in performance is noted in females which are indicated by an extended distance walked while major changes in WSI fitness rises by a mean of only 7%. On the other hand, there is a 26% average percentage increase in MDW for males and a 5% mean increase in WSI fitness. Consequently, the supposition that percentage increase in functional capacity centered on performance (MDW), during ISWT equals change in physiological fitness, based on fall in heart rate at varied workloads is inaccurate and therefore, it should be discarded. Source of match: http://faculty.css.edu/tboone2/asep/Dimpka%2012%281%2910-22.doc Read More