All children answered that MiraLax was tasteless or okay when stirred well into Kool-Aid, fruit juice, or soft drinks.
All 21 children in the MOM group were followed at 1 month (1.1 ± 0.1 month). Fourteen children (67%) were doing well; 6 (29%) were improved; and one child (5%), who did not take the MOM, was not doing well. Frequency of bowel movements / week increased significantly and soiling episodes / week decreased significantly (P < 0.002).
A similar percentage of children in both groups did well, but significantly fewer children in the MiraLax group (64%) were improved compared with the MOM group (95%, P < 0.01; see Fig. 1). Significantly more soiling episodes occurred in children in the MiraLax group than in the MOM group (P < 0.01; see Fig. 3).
Follow-up at 3 Months
The 3-month follow-up occurred as visits in 76% of children and by telephone contact in 22%. One child did not return for follow-up and could not be reached by phone. In the 27 children receiving MiraLax, this follow-up occurred at 3.3 ± 0.8 months. Figures 1 through 3 and Table 2 show the results of the 3-month follow-up. Fifteen children (56%) were doing well, six (22%) were improved, and six (22%) were not doing well. One patient had relapsed. Four patients were taking senna daily, two of them were improved and two were not doing well; all four were rated as not doing well. Their data were excluded from Fig. 2 and 3 and Table 2.
All 21 children in the MOM group were followed up at 3.4 ± 0.8 months. A total of 16 children (76%) were doing well, 4 (19%) were improved, and 1 (5%) was not doing well. One patient was taking daily senna and was not doing well (data excluded from Fig. 2 and 3 and Table 2). The 3-month outcome data did not differ significantly between the two groups (P > 0.1).
Follow-up at 6 Months
The 6-month follow-up occurred with visits in 73% of children and by phone contact in 27%. Figures 1 through 3 and Table 2 show results of the 6-month follow-up. All 28 children in the MiraLax group had follow-up at 6 months (6.6 ± 1.2 months). Fifteen children (54%) were rated as doing well, 4 of whom (14%) had recovered; 5 (18%) were improved; and 8 (29%) were not doing well. Two of the 4 children who were not doing well were siblings from a chaotic family in which compliance was poor. Two more children also required daily senna, neither of whom was doing well or had improved. The data of children on senna are excluded in Fig. 2 and 3 and Table 2.
All 21 children in the MOM group were observed at 6 months (6.9 ± 1.7 months). A total of 14 children (67%) were doing well with 7 (33%) having recovered, one (5%) was improved, and 6 (29%) were not doing well, including 2 children who were switched to MiraLax before the 6-month follow-up visit because of continued refusal to take MOM. At the 6-month follow-up visit, 3 more parents reported that their children refused to take MOM during the past months. These 3 children were switched to MiraLax at the 6-month visit. Therefore, a total of 5 children (24%) in the MOM group had refused MOM during the first 6 months of the study.
Six-month outcome data did not differ significantly between the two treatment groups (P > 0.1).
Follow-up at 12 Months
The 12-month follow-up occurred as visits in 55% of the children and by telephone in 45%. Figures 1 through 3 and Table 2 show results of the 12-month follow-up. All 28 children in the MiraLax group were observed at 11.9 ± 0.9 months. Seventeen children (61%) were doing well, 6 (21%) had recovered, and 11 (39%) were not doing well. Five children also received daily senna; none was doing well or had improved. Their data were excluded from Figs. 2 and 3 and Table 2.
All 21 children in the MOM group were observed at 12.4 ± 0.8 months. Fourteen children (67%) were doing well, 12 (57%) had recovered, and 7 children (33%) were rated as not doing well because they were taking MiraLax after having refused MOM (data excluded from Fig. 2 and 3 and Table 2).
The 12-month outcome data for the MiraLax and MOM groups did not differ significantly, except that the frequency of soiling was significantly higher in the MiraLax group (P < 0.01) (Fig. 3).
In the MiraLax group, the percentage of children complaining of abdominal pain had decreased significantly at each follow-up visit (P < 0.01), and none of the children in the MOM group reported abdominal pain at the 6-month and 12-month follow-ups (Table 2).
In both groups, the percentage of children with daytime wetting decreased (Table 2), but not significantly because of the small number of subjects in each patient group. The percentage of children with daytime wetting decreased significantly at 3-, 6-, and 12-month follow-ups when children in both groups were combined (P < 0.03, P < 0.03, and P < 0.01, respectively).
The percentage of children with nighttime wetting did not change significantly over time (Table 2).
The mean MiraLax dosage at 1 month for children who were doing well or improved was 0.6 ± 0.2 g/kg (range, 0.3 to 1.1 g/kg) and at 3 months was 0.6 ± 0.3 g/kg (range, 0.3 to 1.4 g/kg). The mean dosage did not differ significantly between children with or without initial palpable abdominal fecal masses. The mean MiraLax treatment dosage at 12 months for the 13 children who were doing well or improved and who still required MiraLax was 0.4 ± 0.1 g/kg (range, 0.1 to 0.7). None of the patients required an increased MiraLax dosage over time.
The mean MOM treatment dosage at 1 month for children who were doing well or improved was 1.4 ± 0.6 mL/kg (range, 0.6 to 2.6 mL/kg) and at 3 months was 1.2 ± 0.5 mL/kg (range, 0.6 to 2.4 mL/kg). The mean MOM dosage did not differ significantly between children with or without initial palpable abdominal fecal masses. At 12 months, only two children who were doing well still required MOM. Their dosages were 0.4 and 1.6 mL/kg, both less than the initial treatment dosage. None of the patients required an increased MOM dosage over time.
Five children received a stimulant laxative in addition to MiraLax, and one child received a stimulant laxative in addition to MOM (P > 0.2).
Clinically Significant Side Effects
MiraLax did not cause any significant clinical side effects. Some of the children in the MiraLax group had diarrhea, which may have been responsible for the more frequent soiling episodes as compared with the MOM group. None of the children in the MiraLax group became dehydrated. Children in both groups continued to grow in weight and height during the 12 months. Children receiving MiraLax and their parents did not report increased flatus, abdominal distention, or new onset of abdominal pain.
Noncompliance by children or their caregivers has been a well-known problem in children with functional constipation and encopresis. None of the children reported disliking the taste of MiraLax, and none of the parents reported that a child refused to take the MiraLax in juice or Kool-Aid, whereas 33% of children refused to take MOM. Children's noncompliance with other aspects of the treatment plan is more difficult to assess. Parental noncompliance with administering the laxative and supervising toilet use was a problem in 14% of children in the MiraLax group and in 4% of children in the MOM group.
In this prospective, observational study, we found that MiraLax was palatable, well tolerated, and efficient in the long-term treatment of children with functional constipation and encopresis. At the 1-month, 3-month, 6-month, and 12-month follow-ups, we saw significant improvement in the MiraLax and MOM groups (increased bowel movement frequency and decreased soiling frequency). At the 1- and 12-month follow-ups, children in the MiraLax group reported more soiling than did those in the MOM group (P < 0.01). At 12 months, 61% of children in the MiraLax and 67% of children in the MOM group were doing well (P = 1).
We have no explanation for why children in the MiraLax group had a significantly greater number of soiling episodes at the 1-month and 12-month follow-ups compared with the MOM group. We had observed a few children who developed diarrhea while receiving high doses of MiraLax. Similar observations have been made in initial study weeks when polyethylene glycol was compared with lactulose in constipated adults (22,23).
Abdominal pain decreased significantly, and daytime wetting decreased. Contrary to previous observations (24,25), we did not see a significant decrease in the percentage of children with nighttime wetting.
Recently, polyethylene glycol electrolyte lavage solutions have received increased attention for use as laxatives. Taken rapidly in large volumes, they do not cause net absorption or secretion of electrolytes (26,27). No intestinal absorption occurs at molecular weights exceeding 3,000 (28). No adaptation with consequent flatus or loss of efficiency occurred because no intestinal enzymatic degradation or bacterial metabolism occurred with polyethylene glycol (28). When taken daily in low volumes, polyethylene glycol electrolyte solution is effective, safe, well tolerated, and has no significant side effects in short-term (12) and long-term treatment (13) of constipation in adults. No net absorption or secretion was presumed for the use of smaller volumes, but recent work has shown that low-volume administration resulted in nearly complete absorption of the salt component of the solution, which could potentially lead to dangerous sequelae, especially for patients with renal impairment or congestive heart disease (14,15).
For many years, observational studies were believed to report stronger treatment effects than randomized, controlled trials. Recently, two studies found little evidence that estimates of treatment effects are either consistently larger than or qualitatively different from those obtained in randomized, controlled trials (29,30). However, a randomized, controlled trial comparing these two laxatives has been started, and electrolyte concentrations and hemograms will be checked regularly to evaluate further the efficacy and safety of polyethylene glycol in children with functional constipation and encopresis.
Our observational study shows that polyethylene glycol without electrolytes is a reasonable alternative in the long-term treatment of children with chronic constipation and encopresis. MiraLax did not cause any clinical significant side effects, there was no loss of efficiency during the 12-month study, and none of the children refused the medication because of taste. Soiling episodes decreased significantly over time. At the 12-month follow-up, soiling was more frequently observed in patients treated with MiraLax than in those treated with MOM. This may be because of differences in the patient groups, overtreatment, or noncompliance with all aspects of the treatment plan.
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Keywords:© 2002 Lippincott Williams & Wilkins, Inc.
Polyethylene glycol; Functional constipation; Encopresis; Children; Long-term treatment