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Group and correspondence treatments for weight reduction used in the Multiple Risk Factor Intervention Trial
BEHAVIOR THERAPY 13, 24-30 (1982)
Group and Correspondence Treatments for Weight Reduction Used in the Multiple Risk Factor Intervention Trial ROBERT W . JEFFERY W E N D Y M . GERBER
University of Minnesota Two hundred overweight men participating in the Multiple Risk Factor Intervention Trial were recruited for participation in either a group or correspondence program for weight reduction. Choice of program was found to be related to weight history. Interest in group treatment was higher among those who had gained the most weight in the preceding 3 years. Men participating actively in the correspondence program had the best recent weight history. Active participation in either program led to significant weight losses compared to nonparticipation, and these losses were maintained for 1 year.
Low cost alternatives to intensive face-to-face interventions for dietary change need development for many reasons. These reasons include: (1) the number of individuals needing and seeking dietary programs far exceeds the available time of health professionals, (2) many persons are unable and/or unwilling to commit themselves to time-consuming clinical contact schedules, and (3) face-to-face counseling may be a needless excess for those capable of significant self-direction. The present paper reports on the application of one such low-cost program, a correspondence program for weight reduction provided for participants in the special intervention group of the Minneapolis center of the Multiple Risk Factor Intervention Trial (MRFIT). The MRFIT is a multicenter study evaluating the effectiveness of blood pressure reduction, blood cholesterol reduction, and smoking cessation in reducing morbidity and mortality due to cardiovascular diseases among high risk, middle-aged males. Weight reduction is not a primary intervention target for MRFIT. However, it is encouraged because of its generally positive effects on cholesterol and blood pressure deceleration.
This research was supported by NIH grant N01 HV2 2976C to Henry Blackburn. Requests for reprints should be sent to Robert W. Jeffery, Laboratory of Physiological Hygiene, Stadium Gate 27,611 Beacon Street, S.E., Minneapolis, MN 55455. 24 0005-7894/82/0024~)03051.00/0 Copyright1982by Associationfor Advancementof BehaviorTherapy All rightsof reproductionin any formreserved.
WEIGHT
REDUCTION
TREATMENTS
25
The study population for the Minneapolis center of MRFIT was originally selected from a random survey of over 30,000 households in the surrounding metropolitan area in 1974-75. Men between the ages of 35 and 57 were recruited for the trial if they were in the upper percentiles of estimated risk of coronary disease, based on a multiple logistic of diastolic blood pressure, blood cholesterol, and cigarette smoking. The survey methods and the design of the MRFIT, as well as the multiple risk factor intervention program, have been described elsewhere (Farrand & Mojonnier, 1980; Mandriota, Bunkers, & Wilcox, 1980; The Multiple Risk Factor Intervention Trim Group, 1977). Although previous investigations have documented the potential efficacy of correspondence-based techniques for weight loss, both alone and in comparison to more traditional approaches (Brownell, Heckerman, & Westlake, 1978; Ferstl, Jukusch, & Brengelmann, 1975; Hagen, 1974; Hanson, Borden, Hall, & Hall, 1976; Marston, Marston, & Ross, 1977), the MRFIT population offered unique opportunities to gather additional data on these strategies not available elsewhere. First, because MRFIT participants were selected from a comprehensive survey of urban households and were not self-referred, the attractiveness of the presented programs to the general male population could be more adequately studied. Secondly, because MRFIT participants have been active in Minneapolis since 1975-76, it was possible to relate accurately program effects and participation rates to participants' 3-year history of weight loss efforts. The present investigation (1) examined the attractiveness of correspondence and intensive group approaches to weight loss among overweight MRFIT participants, as measured by enrollment and participation rates, (2) examined the efficacy of the two programs among men actively participating in them, and (3) examined the relationship of weight history to both program interest and efficacy. On a pragmatic level, it was hoped that the correspondence procedure would significantly increase breadth of participation in weight reduction efforts in this population and would prove effective enough to merit continued use.
METHOD
Subjects To form a specific study sample, all special intervention participants in Minneapolis MRFIT with relative weights (cf. The Multiple Risk Factor Intervention Trial Group, 1977)/> 1.15 on November 30, 1978 were sent an introductory letter describing weight reduction options. A return postcard was enclosed upon which men indicated their participation preference, either (1) participation in a group program for weight reduction or (2) participation in a correspondence program for weight reduction. The postcard did not contain an option to indicate no interest at all. Of 200 eligible individuals, 107 returned postcards, 33 selecting the clinic program and 74 choosing the correspondence approach.
26
J E F F E R Y A N D GERBER
Procedure Materials used for the group program and the correspondence program were identical. The core was a nine chapter manual covering the following topics: self-monitoring of eating and exercise, dietary recommendations for weight loss, dietary recommendations for lowering blood cholesterol, exercise recommendations for weight loss, stimulus control techniques, eating style, planning ahead, social support, and motivation. Participants were requested to keep daily records of food intake and exercise. Those in the group program met once a week for 1 hour. Attendance ranged from 10 to 20 individuals. Group meetings consisted of a didactic review of the week's lesson and group discussion. They were led by one or both of the investigators. Participants were weighed and homework collected weekly. For the correspondence program, chapters of the manual were mailed to participants each week. They returned homework and a selfreport of weight by mail. Men who did not respond at all to recruitment attempts were sent a copy of the weight control manual at the beginning of treatment, but no other follow-up. They were considered a minimal program control. Evaluation Strategy At the time of this study, MRFIT policy precluded random assignment of special intervention participants to study groups. Participants were thus allowed to select one of the two weight reduction programs or the minimal program according to personal preference. Efficacy of the programs was evaluated by comparing the performance of men in the three categories over time. Comparability of the groups was examined by studying weight histories prior to the program. Although this design lacks tight experimental control, this weakness is offset in part by the fact that the programs were used in ways that might realistically approximate conditions of use in clinical practice. Program effectiveness was measured by changes in body weight over the 9 weeks of the program, and at 6-month and l-year follow-ups. In addition, MRFIT entry weights and weights for each of the 3 years preceding the study were examined. Those in the group program were weighed with street clothing, less shoes, pre- and posttreatment on a standard balance beam scale. All other weights were taken from MRFIT case files. Each MRFIT participant is weighed at least three times each year at regularly scheduled examinations on a calibrated balance beam scale. Many, such as those on hypertensive medications, are weighed more often. For evaluation purposes the first recorded weight (a) prior to the weight program, (b) following the weight program, (c) following designated 6-month and 1-year follow-up dates, and (d) preceding designated dates for each year prior to initiation of the program were used. This resulted in some differences in the duration of the record intervals among participants, but usually not more than 2 or 3 weeks. The weights at annual examinations were adjusted upward by 3 pounds to account for the fact that participants are weighed without clothing at these times.
WEIGHT
REDUCTION
TREATMENTS
27
RESULTS Of the 200 MRF1T participants recruited for the study, 25 were excluded from program evaluation. Participants were excluded because they were lost to follow-up due to death or moving from the local area (n = 4), because their individual therapist asked that they be excused (n = 6), because they suffered from chronic illnesses (n = 2), failed to show for assessment (n = 7), or indicated a desire not to be included in the program (n = 6). Complete data on weight was available for 16 of the 25 patients excluded from evaluation. Mean weights for this group at MRFIT entry, pretreatment, posttreatment, 6-month and 12-month follow-up intervals were 202.1 pounds, 200.2 pounds, 200.8 pounds, 199.9 pounds, and 200.9 pounds, respectively. The final sample for comparative analyses included 22 men who signed up for group treatment, 67 for correspondence treatment, and 86 for the minimal treatment. Men were divided into five groups: (1) active group participants (n = 13, mean entry weight = 217.2 lbs.), those attending t>50% of group sessions, (2) inactive group participants (n = 9, mean entry weight = 203.2 lbs.), those attending <50% of group sessions, (3) active correspondence participants (n = 18, mean entry weight = 196.4 lbs.), those returning/>50% of homework assignments, (4) inactive correspondence participants (n = 49, mean entry weight = 201.2 lbs.), those returning <50% of homework assignments, and (5) minimal treatment participants (n = 86, mean entry weight = 201.6 lbs.), those not responding to recruitment efforts.
Weight History and Program Participation Weight changes among the groups over time are depicted in Fig. 1. From entry into MRFIT to the end of Year 1, all groups, except those categorized as inactive group participants, lost statistically significant amounts of weight (ts from 1.92 to 4.80, d f from 12 to 85, ps from <.05 to <.001). Over the succeeding 3 years, there was a tendency toward gradual weight gain. The gain was most pronounced in those men who later chose the intensive group program. Weight gain of those who later became active group participants was significantly greater than that of those who became minimal program participants, active correspondence participants, or inactive correspondence participants (ts from 2.17 to 3.34, d f from 29 to 97, ps from <.05 to <.002). Inactive group participants had gained more than either active correspondence participants [t(25) = 2.68, p < .02] or minimal program participants [t(93) = 2.44, p < .02]. One factor prompting men to sign up for an intensive group program seems to have been substantial recent weight gain. Participants with greatest prior weight control success chose the correspondence weight reduction program and actively participated. Weight Changes as a Function of Treatment Over the 8 weeks of treatment, significant reductions in weight occurred among active group participants [t(12) = 3.23, p < .01] and ac-
28
JEFFERY
, --
1.ACTIVE
GROUP
2-INACTIVE
......
AND
GERBER
pARTICIPANTS
GROUP
5.M(N~MA L pROGRAM
PARTICIPANTS
PARTICIPANTS
....®
.j
_
o m
_
~
____~±-__
"~
(J o tu
-5~ ~). . . .
® . . . .
®J
\, ,\ \, \® . . . .
®. . . .
®
-lO-
I BASELINE
FIG.
1.
I YEAR 1
I YEAR 2
I YEAR 3
I I I I PREPOST6 MOS. 12 MOS. PROGRAM P R O G R A M FOLLOW-UP
Changes in weight over time among treatment groups.
tive correspondence participants [t(17) -- 2.64, p < .05]. Inactive group participants lost weight, but not a statistically significant amount, while inactive correspondence participants [t(49) = 3.98, p < .01] and minimal program participants [t(85) = 4.11, p < .01] both experienced significant weight gains. In the first 6 months following treatment, active group participants lost significant additional weight It(12)= 2.64, p < .05]. However, this weight was regained within 1 year. Changes in all other groups during the follow-up year were not significant. For the entire program, from the beginning of treatment to the end of follow-up, significant weight losses occurred in three groups--active group participants [t(12) = 2.64, p < .05], inactive group participants It(8) = 2.41, p < .05], and active correspondence participants [t(17) = 2.15, p < .05]. In contrast, inactive correspondence participants [t(49) = 4.20, p < .01] and minimal program participants [t(85) = 2.45, p < .01] both experienced significant weight gains. Between-group comparisons during treatment showed that both active and inactive group participants, and active correspondence participants lost significant amounts of weight compared to the inactive correspondence and minimal program groups (ts from 3.38 to 5.36, df from 54 to 99, all ps <.001). Identical between-group differences were evident at 6and 12-month follow-ups with one exception--active group participants
WEIGHT REDUCTION TREATMENTS
29
had also lost significantly more than active correspondence participants [t(29) = 2.33, p < .05] at 6-month follow-up.
Total MRFIT Weight Changes Analyses of weight changes from the beginning of MRFIT to the end of the period covered here indicated a nonsignificant mean loss of 1 pound for the entire sample. The only study participants achieving statistically significant losses over the entire period were those actively participating in the correspondence program [t(17) = 3.36, p < .01] and those choosing the minimal program [t(85) = 1.72, p < .05]. Inactive correspondence participants gained a significant amount of weight [t(49) = 2.12, p < .05]. Between-group comparisons showed that active correspondence participants lost significantly more than active group participants [t(29) = 2.42, p < .05], inactive correspondence participants [t(65) = 3.86, p < .001], and minimal program participants [t(102) -- 2.34, p < .03]. Those choosing the minimal program also lost more weight than those in the inactive correspondence condition [t(133) = 2.77, p < .01].
DISCUSSION The MRFIT population is unique. The men were at increased risk of coronary heart disease and had received dietary counseling over several years. The most likely motivated individuals had already achieved normal weight prior to initiation of this study. Although generalization to other populations is thus difficult, several findings from the study are of interest. The relationship between recent weight history and program participation has not been previously examined. Individuals volunteering to participate in an intensive group program for weight reduction had had a difficult recent weight experience. They weighed more than those choosing other treatment options and showed a pronounced trend toward gain in the 3-year period prior to the study. This finding suggests that recent weight gains may contribute significantly to many people's interest in professional assistance for weight control. It also underscores the need to obtain accurate weight histories in an evaluation of the long term effectiveness of weight reduction programs. About half the men enrolling in the group program and three quarters of those signing up for correspondence did not participate actively (less than 50% attendance or homework completion). Inactive group subjects lost significant weight, but inactive correspondence subjects did not. The large nonparticipation rates probably reflect in part recruitment procedures in which potential participants were required to choose between programs regardless of interest. For many, the choice, especially of correspondence, may have been a convenient way to respond without real intention to follow through. Many men may also have felt that their primary commitment to the MRFIT was sufficient to excuse their minimal participation in related intervention programs. Nonparticipation, however, is a problem for many clinical programs (cf. Stunkard & McLarenHume, 1959) and deserves independent study.
30
JEFFERY AND GERBER
Both the group and correspondence approaches to weight loss used here were effective immediately and through 12 months of follow-up for active participants. Assuming that some participants in each type of treatment would have been unwilling to participate in the alternative form, total outreach for the combined approach was undoubtedly greater than had either been offered alone. A proper comparison of relative effectiveness would require a randomized design. From present data, one could argue that best effects for a total population in need would be to offer a wide variety of active weight program options to maximize total participation. The overweight men studied here are showing slow weight gains with passing years. However, different subpopulations showed different response patterns. Those choosing a group approach had gained most in recent years and succeeded at least temporarily in reversing that trend. Those choosing correspondence were of two types: (1) active participants whose participation led to about a doubling of previous weight loss, and (2) inactive participants who continued to gain weight moderately rapidly. Finally are those minimal program individuals not responding to recruitment. Their weight remained relatively stable throughout the treatment and follow-up periods, unaffected by program efforts. It would be of interest to determine if other specialized intervention approaches could be directed toward this group to increase the likelihood of response.
REFERENCES Brownell, K. D., Heckerman, C. L., & Westlake, R . J . Therapist and group contact as variables in the behavioral treatment of obesity. Journal of Consulting and Clinical Psychology, 1978, 4, 593-594. Farrand, M. E., & Mojonnier, L. Nutrition in the multiple risk factor intervention trial (MRFIT): Background and general description. Journal of the American Dietetic Association, 1980, 76, 347-351. Ferstl, R., Jukusch, U., & Brengelmann, J . C . Die verhaltenstherapeutische behandlung des ubergewichts. International Journal of Health Education. 1975, 18, 119-134. Hagen, R. L. Group therapy vs. bibliotherapy in weight reduction. Behavior Therapy, 1974, 5, 222-234. Hanson, R. W., Borden, R. L., Hall, S. M., & Hall, R . G . Use of programmed instruction in teaching self-management skills to overweight adults. Behavior Therapy, 1976, 7, 366-373. Mandriota, R., Bunkers, B., & Wilcox, M. E. Nutrition intervention strategies in the multiple risk factor intervention trial (MRFIT). Journal of the American Dietetic Association, 1980, 77, 138-140. Marston, A. R., Marston, M. R., & Ross, J. A correspondence course behavioral program for weight reduction. Obesity and Bariatric Medicine. 1977, 6, 140-147. Stunkard, A. J., & McLaren-Hume, M. The results of treatment of obesity. A review of the literature and report of a series. Archives oflnternal Medicine, 1959, 103, 79-85. The multiple risk factor intervention trial group. Statistical design considerations in the NHLI multiple risk factor intervention trial (MRFIT). Journal of Chronic Diseases, 1977, 30, 261-275. RECEIVED: January 12, 1981 FINAL ACCEPTANCE: July 28, 1981
Group and Correspondence Treatments for Weight Reduction Used in the Multiple Risk Factor Intervention Trial ROBERT W . JEFFERY W E N D Y M . GERBER
University of Minnesota Two hundred overweight men participating in the Multiple Risk Factor Intervention Trial were recruited for participation in either a group or correspondence program for weight reduction. Choice of program was found to be related to weight history. Interest in group treatment was higher among those who had gained the most weight in the preceding 3 years. Men participating actively in the correspondence program had the best recent weight history. Active participation in either program led to significant weight losses compared to nonparticipation, and these losses were maintained for 1 year.
Low cost alternatives to intensive face-to-face interventions for dietary change need development for many reasons. These reasons include: (1) the number of individuals needing and seeking dietary programs far exceeds the available time of health professionals, (2) many persons are unable and/or unwilling to commit themselves to time-consuming clinical contact schedules, and (3) face-to-face counseling may be a needless excess for those capable of significant self-direction. The present paper reports on the application of one such low-cost program, a correspondence program for weight reduction provided for participants in the special intervention group of the Minneapolis center of the Multiple Risk Factor Intervention Trial (MRFIT). The MRFIT is a multicenter study evaluating the effectiveness of blood pressure reduction, blood cholesterol reduction, and smoking cessation in reducing morbidity and mortality due to cardiovascular diseases among high risk, middle-aged males. Weight reduction is not a primary intervention target for MRFIT. However, it is encouraged because of its generally positive effects on cholesterol and blood pressure deceleration.
This research was supported by NIH grant N01 HV2 2976C to Henry Blackburn. Requests for reprints should be sent to Robert W. Jeffery, Laboratory of Physiological Hygiene, Stadium Gate 27,611 Beacon Street, S.E., Minneapolis, MN 55455. 24 0005-7894/82/0024~)03051.00/0 Copyright1982by Associationfor Advancementof BehaviorTherapy All rightsof reproductionin any formreserved.
WEIGHT
REDUCTION
TREATMENTS
25
The study population for the Minneapolis center of MRFIT was originally selected from a random survey of over 30,000 households in the surrounding metropolitan area in 1974-75. Men between the ages of 35 and 57 were recruited for the trial if they were in the upper percentiles of estimated risk of coronary disease, based on a multiple logistic of diastolic blood pressure, blood cholesterol, and cigarette smoking. The survey methods and the design of the MRFIT, as well as the multiple risk factor intervention program, have been described elsewhere (Farrand & Mojonnier, 1980; Mandriota, Bunkers, & Wilcox, 1980; The Multiple Risk Factor Intervention Trim Group, 1977). Although previous investigations have documented the potential efficacy of correspondence-based techniques for weight loss, both alone and in comparison to more traditional approaches (Brownell, Heckerman, & Westlake, 1978; Ferstl, Jukusch, & Brengelmann, 1975; Hagen, 1974; Hanson, Borden, Hall, & Hall, 1976; Marston, Marston, & Ross, 1977), the MRFIT population offered unique opportunities to gather additional data on these strategies not available elsewhere. First, because MRFIT participants were selected from a comprehensive survey of urban households and were not self-referred, the attractiveness of the presented programs to the general male population could be more adequately studied. Secondly, because MRFIT participants have been active in Minneapolis since 1975-76, it was possible to relate accurately program effects and participation rates to participants' 3-year history of weight loss efforts. The present investigation (1) examined the attractiveness of correspondence and intensive group approaches to weight loss among overweight MRFIT participants, as measured by enrollment and participation rates, (2) examined the efficacy of the two programs among men actively participating in them, and (3) examined the relationship of weight history to both program interest and efficacy. On a pragmatic level, it was hoped that the correspondence procedure would significantly increase breadth of participation in weight reduction efforts in this population and would prove effective enough to merit continued use.
METHOD
Subjects To form a specific study sample, all special intervention participants in Minneapolis MRFIT with relative weights (cf. The Multiple Risk Factor Intervention Trial Group, 1977)/> 1.15 on November 30, 1978 were sent an introductory letter describing weight reduction options. A return postcard was enclosed upon which men indicated their participation preference, either (1) participation in a group program for weight reduction or (2) participation in a correspondence program for weight reduction. The postcard did not contain an option to indicate no interest at all. Of 200 eligible individuals, 107 returned postcards, 33 selecting the clinic program and 74 choosing the correspondence approach.
26
J E F F E R Y A N D GERBER
Procedure Materials used for the group program and the correspondence program were identical. The core was a nine chapter manual covering the following topics: self-monitoring of eating and exercise, dietary recommendations for weight loss, dietary recommendations for lowering blood cholesterol, exercise recommendations for weight loss, stimulus control techniques, eating style, planning ahead, social support, and motivation. Participants were requested to keep daily records of food intake and exercise. Those in the group program met once a week for 1 hour. Attendance ranged from 10 to 20 individuals. Group meetings consisted of a didactic review of the week's lesson and group discussion. They were led by one or both of the investigators. Participants were weighed and homework collected weekly. For the correspondence program, chapters of the manual were mailed to participants each week. They returned homework and a selfreport of weight by mail. Men who did not respond at all to recruitment attempts were sent a copy of the weight control manual at the beginning of treatment, but no other follow-up. They were considered a minimal program control. Evaluation Strategy At the time of this study, MRFIT policy precluded random assignment of special intervention participants to study groups. Participants were thus allowed to select one of the two weight reduction programs or the minimal program according to personal preference. Efficacy of the programs was evaluated by comparing the performance of men in the three categories over time. Comparability of the groups was examined by studying weight histories prior to the program. Although this design lacks tight experimental control, this weakness is offset in part by the fact that the programs were used in ways that might realistically approximate conditions of use in clinical practice. Program effectiveness was measured by changes in body weight over the 9 weeks of the program, and at 6-month and l-year follow-ups. In addition, MRFIT entry weights and weights for each of the 3 years preceding the study were examined. Those in the group program were weighed with street clothing, less shoes, pre- and posttreatment on a standard balance beam scale. All other weights were taken from MRFIT case files. Each MRFIT participant is weighed at least three times each year at regularly scheduled examinations on a calibrated balance beam scale. Many, such as those on hypertensive medications, are weighed more often. For evaluation purposes the first recorded weight (a) prior to the weight program, (b) following the weight program, (c) following designated 6-month and 1-year follow-up dates, and (d) preceding designated dates for each year prior to initiation of the program were used. This resulted in some differences in the duration of the record intervals among participants, but usually not more than 2 or 3 weeks. The weights at annual examinations were adjusted upward by 3 pounds to account for the fact that participants are weighed without clothing at these times.
WEIGHT
REDUCTION
TREATMENTS
27
RESULTS Of the 200 MRF1T participants recruited for the study, 25 were excluded from program evaluation. Participants were excluded because they were lost to follow-up due to death or moving from the local area (n = 4), because their individual therapist asked that they be excused (n = 6), because they suffered from chronic illnesses (n = 2), failed to show for assessment (n = 7), or indicated a desire not to be included in the program (n = 6). Complete data on weight was available for 16 of the 25 patients excluded from evaluation. Mean weights for this group at MRFIT entry, pretreatment, posttreatment, 6-month and 12-month follow-up intervals were 202.1 pounds, 200.2 pounds, 200.8 pounds, 199.9 pounds, and 200.9 pounds, respectively. The final sample for comparative analyses included 22 men who signed up for group treatment, 67 for correspondence treatment, and 86 for the minimal treatment. Men were divided into five groups: (1) active group participants (n = 13, mean entry weight = 217.2 lbs.), those attending t>50% of group sessions, (2) inactive group participants (n = 9, mean entry weight = 203.2 lbs.), those attending <50% of group sessions, (3) active correspondence participants (n = 18, mean entry weight = 196.4 lbs.), those returning/>50% of homework assignments, (4) inactive correspondence participants (n = 49, mean entry weight = 201.2 lbs.), those returning <50% of homework assignments, and (5) minimal treatment participants (n = 86, mean entry weight = 201.6 lbs.), those not responding to recruitment efforts.
Weight History and Program Participation Weight changes among the groups over time are depicted in Fig. 1. From entry into MRFIT to the end of Year 1, all groups, except those categorized as inactive group participants, lost statistically significant amounts of weight (ts from 1.92 to 4.80, d f from 12 to 85, ps from <.05 to <.001). Over the succeeding 3 years, there was a tendency toward gradual weight gain. The gain was most pronounced in those men who later chose the intensive group program. Weight gain of those who later became active group participants was significantly greater than that of those who became minimal program participants, active correspondence participants, or inactive correspondence participants (ts from 2.17 to 3.34, d f from 29 to 97, ps from <.05 to <.002). Inactive group participants had gained more than either active correspondence participants [t(25) = 2.68, p < .02] or minimal program participants [t(93) = 2.44, p < .02]. One factor prompting men to sign up for an intensive group program seems to have been substantial recent weight gain. Participants with greatest prior weight control success chose the correspondence weight reduction program and actively participated. Weight Changes as a Function of Treatment Over the 8 weeks of treatment, significant reductions in weight occurred among active group participants [t(12) = 3.23, p < .01] and ac-
28
JEFFERY
, --
1.ACTIVE
GROUP
2-INACTIVE
......
AND
GERBER
pARTICIPANTS
GROUP
5.M(N~MA L pROGRAM
PARTICIPANTS
PARTICIPANTS
....®
.j
_
o m
_
~
____~±-__
"~
(J o tu
-5~ ~). . . .
® . . . .
®J
\, ,\ \, \® . . . .
®. . . .
®
-lO-
I BASELINE
FIG.
1.
I YEAR 1
I YEAR 2
I YEAR 3
I I I I PREPOST6 MOS. 12 MOS. PROGRAM P R O G R A M FOLLOW-UP
Changes in weight over time among treatment groups.
tive correspondence participants [t(17) -- 2.64, p < .05]. Inactive group participants lost weight, but not a statistically significant amount, while inactive correspondence participants [t(49) = 3.98, p < .01] and minimal program participants [t(85) = 4.11, p < .01] both experienced significant weight gains. In the first 6 months following treatment, active group participants lost significant additional weight It(12)= 2.64, p < .05]. However, this weight was regained within 1 year. Changes in all other groups during the follow-up year were not significant. For the entire program, from the beginning of treatment to the end of follow-up, significant weight losses occurred in three groups--active group participants [t(12) = 2.64, p < .05], inactive group participants It(8) = 2.41, p < .05], and active correspondence participants [t(17) = 2.15, p < .05]. In contrast, inactive correspondence participants [t(49) = 4.20, p < .01] and minimal program participants [t(85) = 2.45, p < .01] both experienced significant weight gains. Between-group comparisons during treatment showed that both active and inactive group participants, and active correspondence participants lost significant amounts of weight compared to the inactive correspondence and minimal program groups (ts from 3.38 to 5.36, df from 54 to 99, all ps <.001). Identical between-group differences were evident at 6and 12-month follow-ups with one exception--active group participants
WEIGHT REDUCTION TREATMENTS
29
had also lost significantly more than active correspondence participants [t(29) = 2.33, p < .05] at 6-month follow-up.
Total MRFIT Weight Changes Analyses of weight changes from the beginning of MRFIT to the end of the period covered here indicated a nonsignificant mean loss of 1 pound for the entire sample. The only study participants achieving statistically significant losses over the entire period were those actively participating in the correspondence program [t(17) = 3.36, p < .01] and those choosing the minimal program [t(85) = 1.72, p < .05]. Inactive correspondence participants gained a significant amount of weight [t(49) = 2.12, p < .05]. Between-group comparisons showed that active correspondence participants lost significantly more than active group participants [t(29) = 2.42, p < .05], inactive correspondence participants [t(65) = 3.86, p < .001], and minimal program participants [t(102) -- 2.34, p < .03]. Those choosing the minimal program also lost more weight than those in the inactive correspondence condition [t(133) = 2.77, p < .01].
DISCUSSION The MRFIT population is unique. The men were at increased risk of coronary heart disease and had received dietary counseling over several years. The most likely motivated individuals had already achieved normal weight prior to initiation of this study. Although generalization to other populations is thus difficult, several findings from the study are of interest. The relationship between recent weight history and program participation has not been previously examined. Individuals volunteering to participate in an intensive group program for weight reduction had had a difficult recent weight experience. They weighed more than those choosing other treatment options and showed a pronounced trend toward gain in the 3-year period prior to the study. This finding suggests that recent weight gains may contribute significantly to many people's interest in professional assistance for weight control. It also underscores the need to obtain accurate weight histories in an evaluation of the long term effectiveness of weight reduction programs. About half the men enrolling in the group program and three quarters of those signing up for correspondence did not participate actively (less than 50% attendance or homework completion). Inactive group subjects lost significant weight, but inactive correspondence subjects did not. The large nonparticipation rates probably reflect in part recruitment procedures in which potential participants were required to choose between programs regardless of interest. For many, the choice, especially of correspondence, may have been a convenient way to respond without real intention to follow through. Many men may also have felt that their primary commitment to the MRFIT was sufficient to excuse their minimal participation in related intervention programs. Nonparticipation, however, is a problem for many clinical programs (cf. Stunkard & McLarenHume, 1959) and deserves independent study.
30
JEFFERY AND GERBER
Both the group and correspondence approaches to weight loss used here were effective immediately and through 12 months of follow-up for active participants. Assuming that some participants in each type of treatment would have been unwilling to participate in the alternative form, total outreach for the combined approach was undoubtedly greater than had either been offered alone. A proper comparison of relative effectiveness would require a randomized design. From present data, one could argue that best effects for a total population in need would be to offer a wide variety of active weight program options to maximize total participation. The overweight men studied here are showing slow weight gains with passing years. However, different subpopulations showed different response patterns. Those choosing a group approach had gained most in recent years and succeeded at least temporarily in reversing that trend. Those choosing correspondence were of two types: (1) active participants whose participation led to about a doubling of previous weight loss, and (2) inactive participants who continued to gain weight moderately rapidly. Finally are those minimal program individuals not responding to recruitment. Their weight remained relatively stable throughout the treatment and follow-up periods, unaffected by program efforts. It would be of interest to determine if other specialized intervention approaches could be directed toward this group to increase the likelihood of response.
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