JOURNAL
OF SURGICAL
RESEARCH
Factors
18,
399-403 (1975)
Determining
Weight
Bypass IGNACIO
Loss after Jejunoileal
for Obesity
J. GUZMAN, M.D., RICHARD L. VARCO, M.D., PH.D. AND HENRY BUCHWALD, M.D., PH.D.
University of Minnesota Hospitals, Minneapolis,
Minnesota 55455
Submitted for publication December 11,1974
The jejunoileal bypass operation is an effective form of treatment in selected cases of morbid obesity. In order to understand the factors that contribute to the degree of weight reduction after this procedure, we have analyzed the following variables: preoperative weight, intraoperative bowel length, age, sex, history of onset of obesity, and average number of bowel movements per day 1 yr postoperatively. Since 1963, 350 patients have undergone jejunoileal bypass by our group at the University of Minnesota. In the first 11 patients an end-to-side anastomosis of 50 cm of jejunum to 5 cm of terminal ileum was done. These patients achieved an 87.4 lb mean weight loss at 1 yr. Eighty percent of these patients stopped losing weight at that time and some regained weight, resulting in a mean weight loss for the group of only 63.5 lb at 3 yr. We considered these results unsatisfactory and modified our technique to employ an end-to-end anastomosis of 40 cm of jejunum to 4 cm of terminal ileum, with drainage of the bypassed bowel, end-to-side, to the cecum. The data which formed the basis for this report are based on the seThe authors extend their gratitude to Edardo Carlos, MS., for his aid in the statistical analysis of these data. Address correspondence and reprint requests to: Henry Buchwald, M.D., Box 290, University of Minnesota Hospitals, Minneapolis, Minnesota 55455. This work supported, in part, by United States Public Service Grant HE-l 1901 and a Special State of Minnesota Legislative Appropriation.
quential study of 74 of our jejunoileal bypass patients with the end-to-end anastomosis. METHODS Weight loss. We have expressed the weight loss in actual pounds lost and in the percentage of ideal weight lost using the New York Life Insurance Company table for medium body builds. Thus, weight loss as a percentage of Ideal Weight = Actual Weight Loss + by Ideal Weight x 100. Preoperative weight. This is given in pounds and in percentage of ideal weight; e.g., a 300-lb individual whose ideal weight is 150lb has a weight of 200% of ideal. Zntraoperative bowel length. This is given in centimeters, measured along the mesenteric border, from the ileocecal valve to the ligament of Treitz, using an umbilical tape knotted every 25 cm. Age. Patient age is given to the nearest year at time of operation. Sex. This variable has been analyzed and mathematically expressed. History of onset of obesity. The patients were divided into two groups dependent on the.presence of obesity prior to the age of 20 or the onset of obesity thereafter. Average number of bowel movements per day postoperatively. These data were
derived from patient interviews 1 yr after the procedure. Statistical analysis. Correlation of variables, linear and multiple regression correlation analyses, and determination of factor significance were carried out using a 399
Copyright o 1975by Academic Press, Inc. All rights of reproduction in any form reserved.
400
JOURNAL
OF SURGICAL
RESEARCH
VOL.
18, NO. 4, APRIL
1975
TABLE 1 Weight Loss in Pounds (% of Ideal Weight) No. yr
No. pts.
Mean
1 2 3
14 45 1
90.6 (70.0) 106 (78.7) 100 (78.1)
Median 84 (65) 98 (77) 93 (74)
computer program of the National Bureau of Standards [3].
Range 23-186 (15-137) 21-200 (13-142) 70-177 (51-138)
Weight
SE
29 (25) 30 (18) -
3.4 (2.9) 4.3 (2.6) -
Loss at One Year
AS A % OF
RESULTS
IDEAL
WEIGHT
= $
x 100
No. Pfs. 74 Mean 70 Median 65 Range 15-137
Weight Loss Weight-loss statistics, up to 3 yr after the jejunoileal bypass procedure are given in Table 1 and graphed in Fig. 1. Mean weight loss at 1 yr was 90.6 lb (70.0% of ideal weight), at 2 yr 106.7 lb (81.7% of ideal weight), and at 3 yr 100 lb (78.4% of ideal weight). A histogram for weight loss at 1 yr is shown in Fig. 2. Weight Loss Correlations Preoperative weight. The mean preoperative weight, as percentage of ideal weight, in this series was 224% (&SD 38, &SE 4.4), with a median weight of 217%, and a range from 152 to 320%. There was a linear correlation of the I-yr weight loss and the mean initial weight, with a correlation coefficient of 0.6247 (Fig. 3). At 2 yr (n = 45), the correlation coefficient was 0.7043.
SD
FIG. 2. Histogram for weight loss, as percent of ideal weight, I yr after jejunoileal bypass.
Admission Weight % Ideal Weight
217 152-320 238
Mean Weight Lost in Pounds I
Coeffhent: 0.6247
200""""'
3631
L mOnth*
2
"
'
" 3
yeorr Time After Surgery
FIG. 1. Mean weight loss in pounds up to 3 yr after jejunoileal bypass in the 74-patient study group.
Admission
Weqhl
I% of IW)
FIG. 3. Upper, histogram of the preoperative weight, as percent of ideal weight; lower, plot of the preoperative weight versus weight loss at 1 yr, both graphed as percent of ideal weight.
GUZMAN,
VARCO AND BUCHWALD:
401
WEIGHT LOSS FACTORS Average Bowel Movements Per Day at One Year Post-Op.
Bowel Length
20r
15 E*I 5 ‘D 10 % d
525 320-600 r98
No. m. Meufl Mecfiun
74 4.1 4
5
Average Bowel hbvemmtr/Dcry (ly post-op.) 2
5or
Corfe/ution Coefficient: 0.2712
FIG. 4. Upper, histogram of intraoperative bowel length in centimeters, measured along the mesenteric border; lower, plot of the bowel length versus the I-yr weight loss as percent of ideal weight.
FIG. 5. Upper, histogram of number of bowel move ments per day at I yr; lower, plot of the number of bowel movements versus weight loss at 1 yr as percent of ideal weight. Correlation coefficient = 0.0486.
Intraoperative bowel length. The mean intraoperative bowel length was 530 cm (&SD 98, &SE 11.3), with a median length of 525 cm. The shortest measured bowel in this series was 320 cm along the mesenteric border; the longest was 800 cm. The correlation coefficients of bowel length and weight loss were 0.2712 at 1 yr (Fig. 4) and 0.4663 at 2 yr. Age. The mean preoperative age of these patients was 35 (*SD 9.6, &SE 0.9), with an age range from 17 to 57; the correlation coefficient with weight loss was 0.1028 at 1 yr (n = 74) and 0.0064 at 2 yr (n = 45). Sex. There were 64 females and 10 males in this study. The females lost an average weight at 1 yr of 7 1.4% of ideal and the males 62.0%. The correlation coefficient for a sex difference and percentage weight loss was 0.1307. This correlation coefficient rose to 0.25 10 at 2 yr. History of onset of obesity. #en the patients were divided between onset of obesity before the age of 20 and thereafter, there was no difference in the weight loss after bypass (69.4% of ideal weight if under 20,68.4% of ideal if over 20).
Average number of daily bowel movements. At 1 yr, the mean number of bowel movements was 4.1 (*SD 2.3, GE 0.26); median 4.0, range l-10. The correlation coefikient with weight loss was 0.0486 (Fig. 5). For 2 yr the correlation coefficient, based on the number of bowel movements 1 yr postoperatively, was 0.1049. SigniJcance of Single Variable Analyses The single regression analyses correlation coefficients and their P values of significance for 1 yr and 2 yr are shown in Table 2. Only the preoperative weight and the intraoperative bowel length were significant at the P < 0.05 level. The number of daily bowel movements gave consistently low and nonsignificant correlation coefficients. Multiple Regression Analysis; Predictive Equation In order to assessthe relative contribution of each of the tested variables of initial weight, intraoperative bowel length, age, sex, and number of bowel movements per day at 1 yr, multiple regression computer analysis was carried out. A predictive equation was
402
JOURNAL OF SURGICAL
RESEARCH VOL. 18, NO. 4, APRIL 1975
TABLE 2 Correlation Analysis of Different Variables with Percent of Ideal Weight One yr (n = 74)
Two yr (n = 45)
Correlation coefficients
Significance
Correlation coefficients
Significance
0.6247
0.0001 0.0194
0.0001
0.2669
0.7043 0.4663 0.0064 0.2510
0.6810
0.1049
0.4927
Initial weight Bowel length Age Sex No. of B.M./day
0.2712 0.1028 0.1307 0.0486
derived. For 1 yr postoperative, this equation related the percentage ideal weight loss to: a negative constant (-34.79); a negative multiple of preoperative age (-0.337); a positive multiple of intraoperative bowel length (+ .059); a positive multiple of the admission weight (+0.383); a negative multiple of sex (-4.154), when male = 1, female = 0; and a positive multiple of the number of daily bowel movements at 1 yr (+0.016). This equation is given in Fig. 6. When the mean values in the 74patient 1 yr follow-up group are inserted into this equation, we get -34.79 - 0.337 (35) + 0.059 (530) + 0.383 (224) - 4.154 (0.135) + 0.016 (4.1) = 69.66%. Of these 74 patients, 69% had a predicted I-yr reduction, expressed as percent of ideal weight, within f 15%of their actual weight loss. The equation was then tested in a separate cohort of 15 patients, i.e., other jejunoileal bypass patients not used in the calculation of the predictive equation. Eleven of the 15 (73%) had a predicted weight loss, expressed as percent of ideal weight, within f 15% of their actual weight loss. In contrast, in the same 15 patients, utilizing the figure of a mean % IDEAL WE’Gt: Loss ONE YEAR *%les
-34.79-0.337 (age) +0.059 (bowel length) +0.383 (admission weight) = -4.154 (sex)* +0.016 (bowel movements per day) = I, Femafes
=0
FIG. 6. Multiple regression predictive equation of I-yr postjejunoileal bypass weight loss, as percent of ideal weight, based on a constant and the variables of: preoperative age, intraoperative bowel length, admission weight, sex, and number of bowel movements per day at 1 yr.
0.3834
0.0012
0.9670 0.8700
weight loss of 70% of ideal weight (the mean derived for the 74-patient test group) yielded only a 40% (6 of 15) predictive accuracy at f 15% of actual weight loss. Thus, the equation appears to have true predictive power with approximately 70% accuracy at &15%. DISCUSSION Several authors have commented on weight loss after a jejunoileal bypass as influenced by the residual length of functioning bowel, the relative proportion of jejunum to ileum in the functioning segment, and the type and site of anastomosis. These considerations are not part of this study. This report concerns itself with the relationship of certain patient variables to the degree of weight loss sustained when a single operative jejunoileal bypass approach was used. Few authors have previously commented on this. Juhl and associates [2] reported 10 patients in whom they left a residual functioning bowel of 37 cm of jejunum anastomosed, end to side, to 13 cm of ileum. At 3 mo the absolute weight loss was the same, irrespective of the patient’s initial weight. We question the significance of these early postoperative findings with an end-toside bypass in only 10 patients. Salmon [4] attempted to correlate weight loss with initial weight; percentage overweight; and length of bypass, as a percentage of total jejunoileal length. His data base consisted of 120 patients subjected to end-to-end anastomosis of the proximal 10 in. of jejunum to the distal 20 in. of ileum. In his study, the only positive correlation of statistical significance was between the rate of weight loss and the initial weight. A similar
GUZMAN,
VARCO AND BUCHWALD:
WEIGHT LOSS FACTORS
403
conclusion-namely, statistically significant correlation of weight loss and initial weight-was reached by Hallberg and Backman [1] who constructed a nomogram to predict weight loss as a function of initial overweight. We plan to extend our computer analysis to additional patients with prospectively predicted weight loss from the multiple regression equation. For practical purposes, since only the initial preoperative weight and the intraoperative total bowel length are highly significant variables and the primary contributors to the predictive equation, it may be possible to predict weight loss for 1 yr, at the time of the jejunoileal bypass operation. A prospective study of this power of prediction is being undertaken. We also plan to develop similar predictive equations, based on retrospective analyses, to estimate the 2-yr, 3-yr, and final weight reduction.
significant variables are age, sex, history of onset of obesity, and the number of bowel movements per day 1 yr after the operation. Using multiple regression analysis for all of the above factors, except for history of onset of obesity, an equation was developed: weight loss (percentage ideal) = -34.79 0.337 (age) + 0.059 (bowel length) + 0.383 (admission weight as percentage ideal) 4.154 (sex, when male = 1, female = 0) + 0.016 (number of bowel movements per day at 1 yr). The equation when tested in a separate cohort of 15 individuals had a predictive power of 73% at f 15% of actual weight loss. For practical purposes, it may be possible to predict, with reasonable accuracy, for the individual patient the actual weight loss to follow a jejunoileal bypass procedure from the patient’s preoperative weight and his intraoperative total small bowel length.
SUMMARY AND CONCLUSIONS We have analyzed in 74 patients 1 yr after jejunoileal bypass and in 45 patients 2 yr after the procedure, the correlation of certain variables with the weight loss achieved. Statistically significant predictive variables, with a high correlation coefficient with the actual weight loss (expressed as the percentage of ideal body weight), are the preoperative weight and the intraoperative total small bowel length. Statistically non-
REFERENCES 1. Hallberg, D., and Backman, L. Kinetics of the body weight after intestinal bypass operation in obesity. Acta Chir. Stand. 139:557,1973. 2. Juhl, E., Quaade, F., and Baden, H. Weight loss in relation to the length of small intestine left in continuity after jejuno-heal bypass shunt operation for obesity. Stand. J. Gastroenterol. 9:219,1974. 3. National Bureau of Standards, Omnitab II, Technical Note 552, pp. 136-155. 4. Salmon, P.A. The results of intestinal bypass operations for the treatment of obesity. Surg. Gynecol. Obstet. 132965,1971.
OF SURGICAL
RESEARCH
Factors
18,
399-403 (1975)
Determining
Weight
Bypass IGNACIO
Loss after Jejunoileal
for Obesity
J. GUZMAN, M.D., RICHARD L. VARCO, M.D., PH.D. AND HENRY BUCHWALD, M.D., PH.D.
University of Minnesota Hospitals, Minneapolis,
Minnesota 55455
Submitted for publication December 11,1974
The jejunoileal bypass operation is an effective form of treatment in selected cases of morbid obesity. In order to understand the factors that contribute to the degree of weight reduction after this procedure, we have analyzed the following variables: preoperative weight, intraoperative bowel length, age, sex, history of onset of obesity, and average number of bowel movements per day 1 yr postoperatively. Since 1963, 350 patients have undergone jejunoileal bypass by our group at the University of Minnesota. In the first 11 patients an end-to-side anastomosis of 50 cm of jejunum to 5 cm of terminal ileum was done. These patients achieved an 87.4 lb mean weight loss at 1 yr. Eighty percent of these patients stopped losing weight at that time and some regained weight, resulting in a mean weight loss for the group of only 63.5 lb at 3 yr. We considered these results unsatisfactory and modified our technique to employ an end-to-end anastomosis of 40 cm of jejunum to 4 cm of terminal ileum, with drainage of the bypassed bowel, end-to-side, to the cecum. The data which formed the basis for this report are based on the seThe authors extend their gratitude to Edardo Carlos, MS., for his aid in the statistical analysis of these data. Address correspondence and reprint requests to: Henry Buchwald, M.D., Box 290, University of Minnesota Hospitals, Minneapolis, Minnesota 55455. This work supported, in part, by United States Public Service Grant HE-l 1901 and a Special State of Minnesota Legislative Appropriation.
quential study of 74 of our jejunoileal bypass patients with the end-to-end anastomosis. METHODS Weight loss. We have expressed the weight loss in actual pounds lost and in the percentage of ideal weight lost using the New York Life Insurance Company table for medium body builds. Thus, weight loss as a percentage of Ideal Weight = Actual Weight Loss + by Ideal Weight x 100. Preoperative weight. This is given in pounds and in percentage of ideal weight; e.g., a 300-lb individual whose ideal weight is 150lb has a weight of 200% of ideal. Zntraoperative bowel length. This is given in centimeters, measured along the mesenteric border, from the ileocecal valve to the ligament of Treitz, using an umbilical tape knotted every 25 cm. Age. Patient age is given to the nearest year at time of operation. Sex. This variable has been analyzed and mathematically expressed. History of onset of obesity. The patients were divided into two groups dependent on the.presence of obesity prior to the age of 20 or the onset of obesity thereafter. Average number of bowel movements per day postoperatively. These data were
derived from patient interviews 1 yr after the procedure. Statistical analysis. Correlation of variables, linear and multiple regression correlation analyses, and determination of factor significance were carried out using a 399
Copyright o 1975by Academic Press, Inc. All rights of reproduction in any form reserved.
400
JOURNAL
OF SURGICAL
RESEARCH
VOL.
18, NO. 4, APRIL
1975
TABLE 1 Weight Loss in Pounds (% of Ideal Weight) No. yr
No. pts.
Mean
1 2 3
14 45 1
90.6 (70.0) 106 (78.7) 100 (78.1)
Median 84 (65) 98 (77) 93 (74)
computer program of the National Bureau of Standards [3].
Range 23-186 (15-137) 21-200 (13-142) 70-177 (51-138)
Weight
SE
29 (25) 30 (18) -
3.4 (2.9) 4.3 (2.6) -
Loss at One Year
AS A % OF
RESULTS
IDEAL
WEIGHT
= $
x 100
No. Pfs. 74 Mean 70 Median 65 Range 15-137
Weight Loss Weight-loss statistics, up to 3 yr after the jejunoileal bypass procedure are given in Table 1 and graphed in Fig. 1. Mean weight loss at 1 yr was 90.6 lb (70.0% of ideal weight), at 2 yr 106.7 lb (81.7% of ideal weight), and at 3 yr 100 lb (78.4% of ideal weight). A histogram for weight loss at 1 yr is shown in Fig. 2. Weight Loss Correlations Preoperative weight. The mean preoperative weight, as percentage of ideal weight, in this series was 224% (&SD 38, &SE 4.4), with a median weight of 217%, and a range from 152 to 320%. There was a linear correlation of the I-yr weight loss and the mean initial weight, with a correlation coefficient of 0.6247 (Fig. 3). At 2 yr (n = 45), the correlation coefficient was 0.7043.
SD
FIG. 2. Histogram for weight loss, as percent of ideal weight, I yr after jejunoileal bypass.
Admission Weight % Ideal Weight
217 152-320 238
Mean Weight Lost in Pounds I
Coeffhent: 0.6247
200""""'
3631
L mOnth*
2
"
'
" 3
yeorr Time After Surgery
FIG. 1. Mean weight loss in pounds up to 3 yr after jejunoileal bypass in the 74-patient study group.
Admission
Weqhl
I% of IW)
FIG. 3. Upper, histogram of the preoperative weight, as percent of ideal weight; lower, plot of the preoperative weight versus weight loss at 1 yr, both graphed as percent of ideal weight.
GUZMAN,
VARCO AND BUCHWALD:
401
WEIGHT LOSS FACTORS Average Bowel Movements Per Day at One Year Post-Op.
Bowel Length
20r
15 E*I 5 ‘D 10 % d
525 320-600 r98
No. m. Meufl Mecfiun
74 4.1 4
5
Average Bowel hbvemmtr/Dcry (ly post-op.) 2
5or
Corfe/ution Coefficient: 0.2712
FIG. 4. Upper, histogram of intraoperative bowel length in centimeters, measured along the mesenteric border; lower, plot of the bowel length versus the I-yr weight loss as percent of ideal weight.
FIG. 5. Upper, histogram of number of bowel move ments per day at I yr; lower, plot of the number of bowel movements versus weight loss at 1 yr as percent of ideal weight. Correlation coefficient = 0.0486.
Intraoperative bowel length. The mean intraoperative bowel length was 530 cm (&SD 98, &SE 11.3), with a median length of 525 cm. The shortest measured bowel in this series was 320 cm along the mesenteric border; the longest was 800 cm. The correlation coefficients of bowel length and weight loss were 0.2712 at 1 yr (Fig. 4) and 0.4663 at 2 yr. Age. The mean preoperative age of these patients was 35 (*SD 9.6, &SE 0.9), with an age range from 17 to 57; the correlation coefficient with weight loss was 0.1028 at 1 yr (n = 74) and 0.0064 at 2 yr (n = 45). Sex. There were 64 females and 10 males in this study. The females lost an average weight at 1 yr of 7 1.4% of ideal and the males 62.0%. The correlation coefficient for a sex difference and percentage weight loss was 0.1307. This correlation coefficient rose to 0.25 10 at 2 yr. History of onset of obesity. #en the patients were divided between onset of obesity before the age of 20 and thereafter, there was no difference in the weight loss after bypass (69.4% of ideal weight if under 20,68.4% of ideal if over 20).
Average number of daily bowel movements. At 1 yr, the mean number of bowel movements was 4.1 (*SD 2.3, GE 0.26); median 4.0, range l-10. The correlation coefikient with weight loss was 0.0486 (Fig. 5). For 2 yr the correlation coefficient, based on the number of bowel movements 1 yr postoperatively, was 0.1049. SigniJcance of Single Variable Analyses The single regression analyses correlation coefficients and their P values of significance for 1 yr and 2 yr are shown in Table 2. Only the preoperative weight and the intraoperative bowel length were significant at the P < 0.05 level. The number of daily bowel movements gave consistently low and nonsignificant correlation coefficients. Multiple Regression Analysis; Predictive Equation In order to assessthe relative contribution of each of the tested variables of initial weight, intraoperative bowel length, age, sex, and number of bowel movements per day at 1 yr, multiple regression computer analysis was carried out. A predictive equation was
402
JOURNAL OF SURGICAL
RESEARCH VOL. 18, NO. 4, APRIL 1975
TABLE 2 Correlation Analysis of Different Variables with Percent of Ideal Weight One yr (n = 74)
Two yr (n = 45)
Correlation coefficients
Significance
Correlation coefficients
Significance
0.6247
0.0001 0.0194
0.0001
0.2669
0.7043 0.4663 0.0064 0.2510
0.6810
0.1049
0.4927
Initial weight Bowel length Age Sex No. of B.M./day
0.2712 0.1028 0.1307 0.0486
derived. For 1 yr postoperative, this equation related the percentage ideal weight loss to: a negative constant (-34.79); a negative multiple of preoperative age (-0.337); a positive multiple of intraoperative bowel length (+ .059); a positive multiple of the admission weight (+0.383); a negative multiple of sex (-4.154), when male = 1, female = 0; and a positive multiple of the number of daily bowel movements at 1 yr (+0.016). This equation is given in Fig. 6. When the mean values in the 74patient 1 yr follow-up group are inserted into this equation, we get -34.79 - 0.337 (35) + 0.059 (530) + 0.383 (224) - 4.154 (0.135) + 0.016 (4.1) = 69.66%. Of these 74 patients, 69% had a predicted I-yr reduction, expressed as percent of ideal weight, within f 15%of their actual weight loss. The equation was then tested in a separate cohort of 15 patients, i.e., other jejunoileal bypass patients not used in the calculation of the predictive equation. Eleven of the 15 (73%) had a predicted weight loss, expressed as percent of ideal weight, within f 15% of their actual weight loss. In contrast, in the same 15 patients, utilizing the figure of a mean % IDEAL WE’Gt: Loss ONE YEAR *%les
-34.79-0.337 (age) +0.059 (bowel length) +0.383 (admission weight) = -4.154 (sex)* +0.016 (bowel movements per day) = I, Femafes
=0
FIG. 6. Multiple regression predictive equation of I-yr postjejunoileal bypass weight loss, as percent of ideal weight, based on a constant and the variables of: preoperative age, intraoperative bowel length, admission weight, sex, and number of bowel movements per day at 1 yr.
0.3834
0.0012
0.9670 0.8700
weight loss of 70% of ideal weight (the mean derived for the 74-patient test group) yielded only a 40% (6 of 15) predictive accuracy at f 15% of actual weight loss. Thus, the equation appears to have true predictive power with approximately 70% accuracy at &15%. DISCUSSION Several authors have commented on weight loss after a jejunoileal bypass as influenced by the residual length of functioning bowel, the relative proportion of jejunum to ileum in the functioning segment, and the type and site of anastomosis. These considerations are not part of this study. This report concerns itself with the relationship of certain patient variables to the degree of weight loss sustained when a single operative jejunoileal bypass approach was used. Few authors have previously commented on this. Juhl and associates [2] reported 10 patients in whom they left a residual functioning bowel of 37 cm of jejunum anastomosed, end to side, to 13 cm of ileum. At 3 mo the absolute weight loss was the same, irrespective of the patient’s initial weight. We question the significance of these early postoperative findings with an end-toside bypass in only 10 patients. Salmon [4] attempted to correlate weight loss with initial weight; percentage overweight; and length of bypass, as a percentage of total jejunoileal length. His data base consisted of 120 patients subjected to end-to-end anastomosis of the proximal 10 in. of jejunum to the distal 20 in. of ileum. In his study, the only positive correlation of statistical significance was between the rate of weight loss and the initial weight. A similar
GUZMAN,
VARCO AND BUCHWALD:
WEIGHT LOSS FACTORS
403
conclusion-namely, statistically significant correlation of weight loss and initial weight-was reached by Hallberg and Backman [1] who constructed a nomogram to predict weight loss as a function of initial overweight. We plan to extend our computer analysis to additional patients with prospectively predicted weight loss from the multiple regression equation. For practical purposes, since only the initial preoperative weight and the intraoperative total bowel length are highly significant variables and the primary contributors to the predictive equation, it may be possible to predict weight loss for 1 yr, at the time of the jejunoileal bypass operation. A prospective study of this power of prediction is being undertaken. We also plan to develop similar predictive equations, based on retrospective analyses, to estimate the 2-yr, 3-yr, and final weight reduction.
significant variables are age, sex, history of onset of obesity, and the number of bowel movements per day 1 yr after the operation. Using multiple regression analysis for all of the above factors, except for history of onset of obesity, an equation was developed: weight loss (percentage ideal) = -34.79 0.337 (age) + 0.059 (bowel length) + 0.383 (admission weight as percentage ideal) 4.154 (sex, when male = 1, female = 0) + 0.016 (number of bowel movements per day at 1 yr). The equation when tested in a separate cohort of 15 individuals had a predictive power of 73% at f 15% of actual weight loss. For practical purposes, it may be possible to predict, with reasonable accuracy, for the individual patient the actual weight loss to follow a jejunoileal bypass procedure from the patient’s preoperative weight and his intraoperative total small bowel length.
SUMMARY AND CONCLUSIONS We have analyzed in 74 patients 1 yr after jejunoileal bypass and in 45 patients 2 yr after the procedure, the correlation of certain variables with the weight loss achieved. Statistically significant predictive variables, with a high correlation coefficient with the actual weight loss (expressed as the percentage of ideal body weight), are the preoperative weight and the intraoperative total small bowel length. Statistically non-
REFERENCES 1. Hallberg, D., and Backman, L. Kinetics of the body weight after intestinal bypass operation in obesity. Acta Chir. Stand. 139:557,1973. 2. Juhl, E., Quaade, F., and Baden, H. Weight loss in relation to the length of small intestine left in continuity after jejuno-heal bypass shunt operation for obesity. Stand. J. Gastroenterol. 9:219,1974. 3. National Bureau of Standards, Omnitab II, Technical Note 552, pp. 136-155. 4. Salmon, P.A. The results of intestinal bypass operations for the treatment of obesity. Surg. Gynecol. Obstet. 132965,1971.
