meticulous construction of the data analysis, statistical tabulation, and interpretation is provided in the following pages.
SPSS was used to manage and calculate the researcher-designed data.
Questions numbered 1-11 were administered as a part of the SF-36 mental inventory. As stated earlier, these questions provide a standard assessment means to assess clinical outcome and mental health. However, they are inadequate to assist in assessing quality of life in patients undergoing on-pump and off-pump by-pass surgery.
Questions 12-30 were research developed and designed to give a more accurate assessment of patient satisfaction with the two procedures. These questions were divided into categories which are representative of factors commonly associated with quality of life. The categories are Mental health, Cognitive ability, Social support, General health, and Bodily pain. Demographic data is contained in questions 21-26 and will be used to identify confounding factors. For purposes of data analysis, the questions will be analyzed according to category and results compared for the two process controls (type of surgery) using descriptive analysis. Confounding factors will be identified and reliability tests conducted using Cronbach's alpha reliability.
Mental health is perhaps the most defining concept of this study. The following tables and charts represent the descriptive statistics of mental health question twelve.
Table 2: Descriptives of Mental Health Question 12 igure 9: Chart of Mental Health Question
As can be seen from the data presented above, the mean for all three researcher-designed mental health questions was slightly higher in the off-pump patients than it was in the on-pump patients, but with a level of significance set at =0.05 the two groups are virtually identical.
This statistical analysis for individual question groups holds true, however these results must be compared across the sample population to determine if results will vary when various demographic data is compared. For instance, women reported four times more than men -- 10.8% of men and 41.1% of women -- that they had, in the past year, "experienced four or more weeks during which they felt sad, blue or depressed or when they lost all interest or pleasure in things that they enjoyed and cared about," as can be seen in the cross-tabulation below. Women who received on-pump CABG were slightly more depressed (5%) than women who received off-pump CABG. A previous study confirmed that women are more likely than men are to experience postoperative depression after CABG surgery attributable to their poor health (Ai, 1997). Several factors were not considered in this evaluation. It is not know if depression is a result of the type of CABG surgery or other factors.
Figure 10: Cross-Tabulation with Gender, Depression, and Surgery Type
Interestingly enough, however, one of the subjects of this study who was reported dead to the researcher by his daughter was a man who committed suicide. He experienced first mild and then severe depression after undergoing on-pump CABG and was admitted to a psychiatric unit for treatment. He spent two months there. The day he was released, he took a kitchen knife and pierced through his chest to his heart. There had been no previous history of depression or any kind of mental illness. He had been a socially and physically active physician prior to his CABG surgery. This case is isolated and it cannot be determined ex-post facto whether or not the suicide was a result of a decrease in quality of life after CABG surgery, or if there may have been other factors unknown to others before surgery that may have contributed to his actions.
Questions 13 and 14 refer to cognitive ability and memory. Questions 15 and 16 refer to bodily pain. Question 17 refers to Health transition. The questions regarding surgical pain, current pain and the frequency of arrythmia are from the SF-36 portion of the survey. The tables and charts below pertain to the five condition specific questions, Cognitive Ability, Memory, Surgical Pain, Current Pain, and frequency of Arrhythmia. The scores range from worse to better for the Cognitive Ability and Memory, from better to worse for the two Pain questions, and from very frequently to never for the Arrhythmia question.
As can be seen from Table 3 above and Figure 11 and Table 4 below, the off-pump patients faired slightly better in every category -- except pain which was evenly split as would be expected because the incisions are identical -- but again, with a level of significance set at =0.05 the two groups are virtually indistinguishable and what little differences are noted, are not enough to be clinically significant.
Figure 11: Chart of Independent Sample T-Test Condition-Specific Questions
Table 4: Descriptive Frequencies of Condition-Specific Questions
The analysis of variance of the condition specific pain further supports that the two groups are virtually indistinguishable. As has been explained above, there is no difference in the incision to the sternum between the on-pump CABG procedure and the off-pump CABG procedure. The alpha reliability coefficients for the two researcher-developed pain questions are.987 and.937.
Table 5: Analysis of Variances for Post-Operative Pain and Current Pain
Figure 12: Post-Surgical Pain and Current Surgical Pain
Social Support Questions
Questions 18, 19, and 20 related to the level of social support that the patients received. The social support data showed that all respondents had either family members or pets that lived with them. Using Cronbach's alpha reliability, coefficients were calculated for the Mental Health Component Score and the Family-Pet support system. The reliability score was 0.977.
The figures on the next page show the scaled frequency in the family-pet support questions. One-hundred percent of the respondents had family members and/or pets living with them. Not a single respondent lived alone. Since all respondents had a social support system in place, it is doubtful that lack of a social support system contributed to any depression found, but a multivariate analysis is run in a later section to see if this is or is not the case. The question regarding social support, in this case, serves to rule out a confounding factor to the research question. This data serves to demonstrate that social support was not a factor in the overall mental health of the patients.
One patient actually wrote on her questionnaire that her family and friends would not let her get depressed, but she did admit that she had been depressed for a short period after surgery and felt that her sex life to this day, had been damaged due to her surgery. CABG surgery is particularly hard on women if the Saphenous vein is taken instead of one of the arteries. In addition to having a scar down the middle of their chest, taking the vein requires an incision down the length of the leg and results in a scar on the leg that is about two feet long. The patient had only been married a couple of years when the surgery was preformed. Depression in women may have more to do with self-image than declining health as the studies show (Ai, 1997). However, this data was not a part of this study and would be interesting material for further study.
The additional retrospective Likert scale question, which asked, "The way I would have answered the questions in this survey before my heart operation would be," was virtually split. The on-pump patients had a mean of 2.48 and the off-pump patients had a mean of 2.53, once again slightly better, but not clinically significant with an alpha coefficient reliability score of 0.794. Level of significance was set a =0.05.
Figure 13: Chart of Family Members in the Home
Figure 14: Cart of Pets in the Home
Figure15: General Linear Multivariate Chart of all Mental Health, Condition Specific, and Social Support Researcher-Designed Questions
Summary of Descriptive Statistics for Individual Traits and Characteristics.
Mental Health: On Question 12a, the mean for on-pump was 1.83 and for off pump it was 1.97, on Question 12b, the mean for on-pump was 1.80 and for off pump it was 1.86, and on Question 12c, the mean for on-pump was 1.79 and for off pump it was 1.89. Since these three questions are dichotomous, yes (1) or no (2) questions, the higher the mean the stronger the score.
Condition Specific: For Question 13 the mean for on-pump was 2.83 and for off pump it was 3.06. For Question 14 the mean for on-pump was 2.74 and for off pump it was 2.97. For Question 17 the mean for on-pump was 4.23 and for off pump it was 4.33. Since these three questions were Likert scale questions that moved from worse to better the higher the mean the stronger the score. For Question 15 the mean for on-pump was 2.56 and for off pump it was 2.67. For Question 16 the mean for on-pump was 2.32 and for off pump it was 2.15. Since these two questions were Likert Scale questions that moved from better to worse the lower the mean…