Effects of interventions
Comparison one: controlled trials of exclusive versus mixed breastfeeding for four to six months, developing countries
Two studies were found in this category, both from the same group of investigators and involving the same study setting (Honduras). The first of these studies, Cohen 1994a, involved term infants unselected for birthweight but included 29 infants (19.9%) weighing less than 2500 g at birth. The second, Dewey 1999a, was restricted to term infants weighing less than 2500 g at birth. The quality ratings of these two trials were not high for several reasons. First, in both trials, allocation was within clusters defined by weeks, rather than to individual women, yet the results were analyzed with individual women and infants as the units of analysis; any similarities in outcome within weeks (intracluster correlation) would tend to reduce the true effective sample size and thereby overestimate the precision (i.e., underestimate the variance) of the results. Second, the first trial allocated the weeks by alternation, rather than by strict randomization, thereby creating a potential for nonconcealment and uncontrolled confounding bias at enrollment (although there is no evidence that such bias actually occurred). Third, the published results were not based on analysis by intention to treat. Most of the babies not analyzed in these two trials were truly lost to follow up; however, rather than excluded for noncompliance, the latter were restricted to four babies (three in the exclusive breastfeeding (EBF) group, one in the mixed breastfeeding (MBF) group) in the first trial and three babies (all three in the exclusive breastfeeding group) in the second trial. Moreover, the investigators have provided (unpublished) data on weight and length gain on five of the nine dropouts in the second Honduran trial (three of the nine moved away before six months), thereby substantially reducing the potential for selection bias in the analysis of that trial.
Most importantly, despite the above-noted methodological problems, these two trials are the only studies uncovered by our search that used an experimental design to specifically address the four to six months versus 'about six months' controversy. Thus, at least with respect to bias due to known and unknown confounding variables, these trials are methodologically superior to any of the observational studies included in this review despite their methodological imperfections. Furthermore, the investigators made a considerable effort to ensure compliance with the assigned allocation and to standardize the training of the observers who performed the anthropometric measurements, thereby reducing the random error (improving the precision) of these measurements. Finally, detailed comparisons between trial participants and eligible nonparticipants demonstrated no differences that would detract from the external validity (generalizability) of the trials' findings, at least for the specific type of setting where the study was conducted (an urban, low-income population in Honduras).
For all analyses, the two mixed breastfeeding groups (one of which was intended to maintain frequency of breastfeeding) in the first trial were combined for the purposes of this analysis. Monthly weight gain from four to six months was nonsignificantly slightly higher among infants whose mothers were assigned to continued exclusive breastfeeding (weighted mean difference (WMD) +20.78; 95% confidence interval (CI) -21.99 to +63.54 g/mo) (outcome one). Thus the 95% CI is statistically compatible with a weight gain only 22 g/mo lower in the EBF group, which represents approximately 5% of the mean and 15% of the standard deviation (SD) for the monthly weight gain. Weight gain from 6 to 12 months (outcome two) was almost identical in the two groups (WMD -2.62; 95% CI -25.85 to +20.62 g/mo).
For length gain from four to six months, the WMD was 1.0 mm/mo (95% CI -0.40 to +2.40 mm/mo); the lower confidence limit represents only 2% of the mean and 8% of the SD for monthly length gain (outcome three). As with weight gain, length gain from 6 to 12 months (outcome four) was nearly identical in the two groups (WMD -0.4; 95% CI -1.0 to +0.2 mm/mo).
Weight-for-age, length-for-age, and weight-for-length z-scores at six months (outcomes five to seven) were all nonsignificantly higher in the EBF group (WMD +0.18; 95% CI -0.06 to +0.41; WMD +0.11; 95% CI -0.11 to +0.33; and WMD +0.09; 95% CI -0.13 to +0.31, respectively).
The impact of the small sample size of the two Honduran trials is evident when examining the risk of undernutrition, as represented by anthropometric z-scores less than -2 at six months (outcomes 8 to 10). For weight-for-age, the pooled RR was 2.14 (95% CI 0.74 to 6.24), which is statistically compatible with a six-fold increase in risk. The results were somewhat more reassuring for length-for-age (RR 1.18; 95% CI 0.56 to 2.50) but not for weight-for-length (RR 1.38; 95% CI 0.17 to 10.98).
All hematologic results (outcomes 11 to 19) are based on the first Honduras trial (Cohen 1994a), since in the second trial (Dewey 1999a, restricted to low birthweight infants), infants with low hemoglobin concentrations at two and four months were supplemented with iron. A nonsignificantly higher proportion of infants in the exclusively breastfed group received iron supplements from six to nine months (RR 1.20; 95% CI 0.91 to 1.58) (outcome 11). This is consistent with the significantly lower average hemoglobin concentration at six months in the exclusively breastfed group (difference = -5.00 (95% CI -8.46 to -1.54) g/L) (outcome 12). A nonsignificantly higher proportion of exclusively breastfed infants had a hemoglobin concentration below 110 g/L at six months (RR 1.20; 95% CI 0.91 to 1.58) (outcome 13). Similarly, mean plasma ferritin concentration was significantly lower at six months in the exclusively breastfed infants (difference = -18.90 (95% CI -37.31 to -0.49) mcg/L), with a RR for a low (less than 15 mcg/L) ferritin concentration of 2.93 (95% CI 1.13 to 7.56) (outcomes 17 and 19).
In the second trial, no significant effect was seen on the proportion of infants with a low zinc concentration (less than 70 mcg/dL) at six months (RR 0.75; 95% CI 0.43 to 1.33) (outcome 20).
In the pooled results from both Honduran trials, no significant difference was seen between the EBF and MBF groups for the percentage of days with fever, cough, or nasal congestion, nasal discharge, hoarseness, or diarrhea from four to six months (outcomes 21 to 26), nor for fever, nasal congestion, or diarrhea from 6 to 12 months (outcomes 27 to 29).
Again based on pooled results from both trials, mothers in the exclusively breastfed group reported that their infants crawled at an average of 0.80 (95% CI 0.34 to 1.26) months sooner (outcome 30). No difference was seen, however, in the mean age at which the infants were reported to have first sat from a lying position (WMD -0.17 (95% CI -0.56 to +0.21) months) (outcome 31). The results from the two Honduras trials (Cohen 1994a; Dewey 1999a) differed with respect to maternal reports of walking by 12 months (outcome 32), with a significantly lower proportion of exclusively breastfed infants reported as not having walked by 12 months in the first trial (RR 0.66; 95% CI 0.45 to 0.98), but a nonsignificantly higher proportion not having done so in the second trial (RR 1.12; 95% CI 0.90 to 1.38), with statistically significant (P < .01) heterogeneity between the two trials.
Mothers in the exclusively breastfed group (from the two trials combined) had a statistically significantly larger weight loss from four to six months (WMD 0.42; 95% CI 0.02 to -0.82) kg) (outcome 33). Women in the exclusively breastfed group were also nonsignificantly less likely to have resumed menses by six months postpartum (RR 0.58 (95% CI 0.33 to 1.03); the effect was statistically significant in the second Honduras trial when considered alone (RR 0.35; 95% CI 0.14 to 0.91) (outcome 34).
Comparison two: observational studies of exclusive versus mixed breastfeeding for three to seven months, developing countries
The main concern in using an observational design to compare outcomes with EBF versus MBF is confounding due to differences in socioeconomic status, water and sanitation facilities, parental size (a proxy for genetic potential), and (perhaps most importantly) weight and length at the time complementary foods were first introduced in the mixed breastfeeding group. The latter source of confounding (i.e., by indication) will arise if poorly-growing infants are more likely to receive complementary foods.
Four cohort studies in this category from Peru (Brown 1991a), the Philippines (Adair 1993a), Senegal (Simondon 1997a), and Iran (Khadivzadeh 2004) found no evidence of confounding by indication, Adair 1993a found no confounding by several other potential factors, and (in unpublished data provided by the authors) Simondon 1997a calculated adjusted means for weight and length gain from four to six months. Nonetheless, the inability of observational studies to control for subtle (and unknown) sources of confounding and selection bias suggests the need for cautious interpretation. All four studies reported on monthly weight gain from four to six months (outcome one). The WMD was -10.10 (95% CI -27.68 to +7.48) g/mo, a lower confidence limit compatible with a deficit of only 7% of the mean and less than 15% of the SD for monthly weight gain. The Simondon 1997a study also reported on monthly weight gain from six to nine months (difference = -6.00 (95% CI -54.15 to +42.15) g/mo) (outcome two). All four studies also reported on monthly length gain from four to six months (outcome three); the WMD was +0.4 (95% CI -0.2 to +1.1) mm/mo, a lower confidence limit statistically compatible with a reduced length gain in the EBF group less than 2% of the mean and 4% of the SD. The Simondon 1997a study also reported on monthly length gain from six to nine months (outcome four), and again the results excluded all but a small reduction in the exclusively breastfed group (difference = +0.4 (95% CI -0.6 to +1.4) mm/mo).
Onayade 2004 actually reported significantly higher absolute weights at both five and six months in the EBF group but did not analyze weight gains; the absence of control for confounding differences between the EBF and MBF groups, as well as the possibility of reverse causality (i.e., those infants with lower weights may have been more likely to receive complementary feeding) argue for cautious interpretation, however.
The Simondon 1997a study also provided (unpublished) data on anthropometric z-scores and mid-upper arm circumference. EBF was associated with nonsignificantly higher WMD z-scores at six to seven and 9 to 10 months: +0.13 (95% CI -0.09 to +0.35) and +0.09 (95% CI -0.15 to +0.33), respectively, for weight-for-age (outcomes five and six); +0.04 (95% CI -0.14 to +0.22) and +0.11 (95% CI -0.09 to +0.31), respectively, for length-for-age (outcomes seven and eight); and +0.11 (95% CI -0.09 to +0.31) and +0.01 (95% CI -0.21 to +0.23), respectively, for weight-for-length (outcomes 9 and 10). The relative risks for low (less than -2) z-scores at six to seven and 9 to 10 months were 0.92 (95% CI 0.54 to 1.58) and 0.93 (95% CI 0.64 to 1.36), respectively, for weight-for-age (outcomes 11 and 12); 1.20 (95% CI 0.57 to 2.53) and 1.21 (95% CI 0.62 to 2.37), respectively, for length-for-age (outcomes 13 and 14); and 0.42 (95% CI 0.12 to 1.50) and 0.82 (95% CI 0.39 to 1.71), respectively, for weight-for-length (outcomes 15 and 16). Mid-upper arm circumference was nonsignificantly higher in the EBF group at both six to seven and 9 to 10 months: WMD +2.0 (95% CI -0.4 to +4.4) mm and +1.0 (95% CI -1.6 to +3.6) mm, respectively (outcomes 17 and 18).
Huffman 1987 reported a longer median duration of lactational amenorrhea associated with EBF (for ³7 months) versus MBF (16.1 versus 15.3 months, respectively), but means and SDs were not reported. In a multivariate (Cox) regression model adjusting for maternal education, parity, religion, and weight, EBF for ³6 months was associated with a significantly longer time to resumption of menses versus EBF for less than one month, but no direct comparison was reported versus MBF. Simondon 1997a reported a lower risk of resumption of menses by six to seven months (outcome 21) in the EBF group: crude RR 0.19 (95% CI 0.05 to 0.79), adjusted odds ratio (OR) 0.19 (95% CI 0.04 to 0.86).
Khadivzadeh 2004 found a lower incidence of both gastrointestinal (11 versus 27%; RR 0.41; 95% CI 0.21 to 0.78) and respiratory (23 versus 35%; RR 0.68; 95% CI 0.43 to 1.06) infection at four to six months in the EBF group (outcomes 19 and 20). Onayade 2004 reported corresponding crude ORs of 0.02 (95% CI 0.01 to 0.09) and 0.43 (95% CI 0.17 to 1.00), respectively, but did not provide numerators and denominators and did not control for confounding differences between the EBF and MBF groups.
Cross-sectional studies share all of the methodological shortcomings of other observational designs (see above) plus one important additional one: selective loss to follow up. In particular, children who die, are hospitalized, or are referred to a site other than the one under study, may be more likely to experience morbidity or suboptimal growth. If such (unstudied) infants are more heavily represented in one of the feeding groups, the resulting comparison will be biased.
One large cross-sectional study from Chile (Castillo 1996) reported a similar risk of weight-for-age z-score less than -1 and height-for-age z-score less than -1 from three to five and six to eight months in the two feeding groups, but the prevalences, CIs, and standard errors for the reported prevalence ratios are not published, thus precluding any assessment of sampling variation.
Comparison three: observational studies of prolonged (more than six months) exclusive versus mixed breastfeeding, developing countries
One small cross-sectional study from Pune, India (Rao 1992) permitted analysis only of male infants, since a relatively large fraction of female infants in the MBF group received artificial feeding in the first six months of life. The results (outcome one) showed a nonsignificant reduction of low (less than 75% of the reference mean ) weight-for-age at 6 to 12 months of age in the exclusively breastfed males (RR 0.61; 95% CI 0.26 to 1.43). The strong possibility of confounding by age, even within the range of 6 to 12 months (the EBF group is likely to have been younger, on average, and therefore less undernourished), further limits the reported result.
A cohort study from Bangladesh (Khan 1984) reported similar weight and length gains in infants who were exclusively breastfed, those who were breastfed with supplements beginning at 6 to 11 months, and those who were exclusively breastfed for 12 months and supplemented between 12 and 15 months. Unfortunately, the data are presented only graphically and without standard deviations, thus preventing a quantitative assessment or pooling with data from other studies.
Comparison four: observational studies of exclusive versus mixed breastfeeding for three to seven months, developed countries
A pooled sample of breastfed infants from seven studies carried out in six developed countries (WHO 1994a), a pooled analysis from five countries (two developed, three developing, but in which study women were all literate and of middle to high socioeconomic status) (WHO 1997), a large cohort study nested within a randomized trial in Belarus (Kramer 2000a), and a small study from Sweden (Akeson 1996a) reported on weight gain between three and eight months. WHO 1997 and Kramer 2000a controlled for confounding by indication (size or growth in first three to four months) and other potential confounders using multilevel (mixed) regression analyses. Statistically significant (P = .02) heterogeneity was observed among the four studies, with considerably larger mean weight gains in both groups from Belarus and a slightly but significantly higher gain in the MBF group (outcome one). Because of this heterogeneity, the WMD of -12.45 (95% CI -23.46 to -1.44) g/mo should be interpreted with caution; even the lower 95% confidence limit of this estimate, however, is compatible with a lower weight gain in the EBF group of less than 4% of the mean and less than 15% of the SD for the Belarussian study. Moreover, given the large weight gains in both groups in the Belarussian study, the higher gain in the MBF group is not necessarily a beneficial outcome. Heinig 1993 and Kramer 2000a also reported on weight gain between six and nine months (outcome two). Again, the results show significant heterogeneity (P = .04) but are dominated by the larger size of the Belarussian study. The pooled WMD was -2.26 (95% CI -16.94 to +12.42) g/mo. Akeson 1996a, Heinig 1993, and Kramer 2000a reported on weight gain from 8 to 12 months (outcome three); the WMD was -1.82 (95% CI -16.72 to +13.08) g/mo, which excludes a reduced length gain in the EBF group of 5% of the mean and 10% of the SD for the Belarussian study.
For length gain at three to eight months (outcome four), the studies again show significant (P < .01) heterogeneity. Kramer 2000a found a slightly but significantly lower length gain in the EBF group at four to eight months (difference -1.1 (95% CI -1.7 to -0.5) mm/mo), whereas the pooled analysis yielded a WMD of -0.4 (95% CI -0.7 to 0.0) mm/mo; the lower confidence limit is statistically compatible with a reduced length gain of less than 4% of the mean and 10% of the SD for the Belarussian study. Heinig 1993 and Kramer 2000a also reported on length gain at six to nine months (WMD -0.4 (95% CI -1.0 to +0.1) mm/mo) (outcome five). For the eight to 12 month period, the results show a slightly but significantly higher length gain in the EBF group (WMD +0.9 (95% CI +0.3 to +1.4)) mm/mo (outcome six).
Observational analyses from the Belarussian study (Kramer 2000a) also include data on weight-for-age, length-for-age, and weight-for-length z-scores at six, nine, and 12 months. Means in both the EBF and MBF groups were well above (+0.5 to +0.6) the reference values at all three ages. Nonetheless, the weight-for-age z-score was slightly but significantly lower in the EBF group at all three ages: WMD -0.09 (95% CI -0.16 to -0.02) at six months, -0.10 (95% CI -0.18 to -0.02) at nine months, and -0.09 (95% CI -0.17 to -0.01) at 12 months (outcomes seven to nine). Length-for-age z-scores were very close to the reference (0) at six and nine months and slightly above the reference (0.15) at 12 months. Again, the EBF group had slightly but significantly (except at 12 months) lower values: WMD -0.12 (95% CI -0.20 to -0.04) at six months, -0.14 (95% CI -0.22 to -0.06) at nine months, and -0.02 (95% CI -0.10 to +0.06) at 12 months (outcomes 10 to 12). Mean weight-for-length z-scores were high and rose (from about 0.65 to 0.80) from 6 to 12 months, with no significant differences between the EBF and MBF groups at any age: WMD +0.02 (95% CI -0.07 to +0.11) at six months, +0.03 (95% CI -0.06 to +0.12) at nine months, and -0.08 (95% CI -0.17 to +0.01) at 12 months (outcomes 13 to 15).
The prevalence of low (less than -2) z-scores did not differ significantly in the two Belarussian feeding groups for any of the three z-scores at any of the three ages, although the small number of infants with low z-scores provided low statistical power to detect such differences. RRs (and 95% CIs) for low weight-for-age were 0.92 (0.04 to 19.04) at six months, 1.52 (0.16 to 14.62) at nine months and 1.15 (0.13 to 10.31) at 12 months (outcomes 16 to 18). For length-for-age, the corresponding figures were 1.53 (0.84 to 2.78) at six months, 1.46 (0.80 to 2.64) at nine months, and 0.66 (0.23 to 1.87) at 12 months (outcomes 19 to 21). For weight-for-length, the figures were 0.31 (0.02 to 5.34) at six months, 1.14 (0.24 to 5.37) at nine months, and 1.15 (0.13 to 10.31) at 12 months (outcomes 22 to 24).
The Belarussian study also provided data on head circumference. No significant differences were observed at six months (difference -1.0 (95% CI -2.3 to +0.3) mm) (outcome 25) or nine months (+0.7 (95% CI -0.6 to +2.0) mm) (outcome 26), but the EBF group had a slightly but significantly larger circumference at 12 months (outcome 27): difference = +1.9 (95% CI +0.6 to +3.2) mm.
Heinig 1993 reported nearly identical sleeping time (729 versus 728 minutes/day) in the two groups (outcome 28). Akeson 1996a reported similar total amino acid and essential amino acid concentrations at six months of age in the two feeding groups (outcomes 29 and 30). Both Kramer 2000a and a cohort study from Finland (Kajosaari 1983) reported an atopic eczema at one year (outcome 31). The two studies showed statistically significant (P = .03) heterogeneity, with Kajosaari 1983 reporting a significantly reduced risk (RR 0.40; 95% CI 0.21 to 0.78), but the larger Belarussian study finding a much lower absolute risk in both feeding groups and no risk reduction with EBF (RR 1.00; 95% CI 0.60 to 1.69). Although Kajosaari 1983 also reported a reduced risk of a history of food allergy (outcome 32), double food challenges showed no significant risk reduction (RR 0.77; 95% CI 0.25 to 2.41) (outcome 33). Neither Oddy 1999 nor Kramer 2000a found a significant reduction in risk of recurrent (two or more episodes) wheezing in the EBF group (pooled RR 0.79; 95% CI 0.49 to 1.28) (outcome 34). In the Kajosaari 1983 study, the reduction in risk of any atopy at five years (outcome 35) in the EBF group was nonsignificant (RR 0.68; 95% CI 0.40 to 1.17), and no reduction in risk was observed for atopic eczema (RR 0.97; 95% CI 0.50 to 1.89) (outcome 36). A reduction in risk of borderline significance was observed for pollen allergy at five years (RR 0.53; 95% CI 0.28 to 1.01) (outcome 37). Both Kajosaari 1983 and Oddy 1999 reported on risk of asthma at five to six years (outcome 38); the pooled RR was 0.91 (95% CI 0.61 to 1.36). Reduced risks of history of food allergy (RR 0.61; 95% CI 0.12 to 3.19) (outcome 39) and allergy to animal dander (RR 0.81; 95% CI 0.24 to 2.72) at five years (outcome 40) were far from achieving statistical significance. Oddy 1999 found no reduction in risk of a positive skin prick test at six years in the EBF group (RR 0.99; 95% CI 0.73 to 1.35) (outcome 41).
A small Italian study of hematologic outcomes at 12 months by Pisacane in 1995 reported a statistically significantly higher hemoglobin concentration (117 versus 109 g/L (95% CI for the difference = +4.03 to +11.97 g/L)) (outcome 42), a nonsignificant reduction in anemia (hemoglobin less than 110 g/L) (RR 0.12; 95% CI 0.01 to 1.80) (outcome 43), a nonsignificantly higher ferritin concentration (WMD +4.7; 95% CI -6.3 to +15.7 mcg/L) (outcome 44), and a nonsignificant reduction in the risk of low (less than 10 mcg/L) ferritin concentration (RR 0.42; 95% CI 0.12 to 1.54) (outcome 45) among infants in the EBF group. Of note in this study is that the exclusive and mixed breastfeeding continued in both groups until at least 12 months (a criterion for selection into the Pisacane 1995 study).
Kramer 2000a recorded only one and two deaths (outcome 46) among the 621 and 2862 Belarussian infants in the EBF and MBF groups, respectively (RR 2.30; 95% CI 0.21 to 25.37). The EBF had a significantly reduced risk of one or more episodes of gastrointestinal infection in the first 12 months of life (RR 0.67; 95% CI 0.46 to 0.97) (outcome 47), which was maintained in a multivariate mixed model controlling for geographic origin, urban versus rural location, maternal education, and number of siblings in the household (adjusted OR 0.61; 95% CI 0.41 to 0.93). No significant reduction in risk was observed for hospitalization for gastrointestinal infection, however (RR 0.79; 95% CI 0.42 to 1.49) (outcome 48). In the above-mentioned Australian cohort study, Oddy 1999 found no significant reduction of risk for one or more episodes of upper respiratory tract infection (outcome 49) in the EBF group (RR 1.07; 95% CI 0.96 to 1.20). Neither Oddy 1999 nor Kramer 2000a found a significantly reduced risk of two or more such episodes (pooled RR 0.91; 95% CI 0.82 to 1.02) (outcome 50). Nor did Oddy 1999 find a significant reduction in risk of four or more episodes of upper respiratory infection (RR 0.82; 95% CI 0.52 to 1.29) (outcome 51) or of one or more episodes of lower respiratory tract infection (RR 1.07; 95% CI 0.86 to 1.33) (outcome 52). Kramer 2000a found a small and nonsignificant reduction in risk of two or more respiratory tract infections (upper and lower combined) (RR 0.90; 95% CI 0.79 to 1.03) (outcome 53). The combined crude results of Oddy 1999 and Kramer 2000a show a substantial and statistically significant reduction in risk for hospitalization for respiratory tract infection (pooled RR 0.75; 95% CI 0.60 to 0.94), but the crude risk reduction in Kramer 2000a was nearly abolished and became statistically nonsignificant in a multivariate mixed model controlling for geographic region, urban versus rural location, maternal education and cigarette smoking, and number of siblings in the household (adjusted OR 0.96; 95% CI 0.71 to 1.30) (outcome 54).
In a study from Tucson, Arizona, (Duncan 1993) reported no difference in the average number of episodes of acute otitis media in the first 12 months of life (outcome 55) in the exclusive versus MBF groups (1.48 versus 1.52 episodes, respectively) (95% CI for the difference -0.49 to +0.41 episodes). Duncan 1993 and Kramer 2000a both found a slightly elevated risk for one or more episodes of otitis media (pooled RR 1.28; 95% CI 1.04 to 1.57) (outcome 56), but Duncan 1993 found a nonsignificant reduction in risk for frequent otitis media (RR 0.81; 95% CI 0.43 to 1.52) (outcome 57).
Comparison five: observational studies of prolonged (more than six months) exclusive versus mixed breastfeeding, developed countries
A small observational cohort study from the Baltimore-Washington area (U.S.) (Ahn 1980) reported "no differences in the overall rates of gain in weight and length" for the first year of life in infants who were exclusively breastfed beyond six months versus those exclusively breastfed for less than six months and mixed breastfed thereafter. The actual data were not reported, however, and thus cannot be assessed quantitatively in this review.
One small Finnish study (Savilahti 1987a) reported no difference in lipid concentrations at nine months among infants exclusively breastfed for nine months versus those exclusively breastfed for six months and mixed breastfed from six to nine months. Similar concentrations were observed for very low density lipoprotein, low density lipoprotein, high-density lipoprotein-2, high-density lipoprotein-3, apoprotein B, and total triglycerides (outcomes one to six).