This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Evaluating the Effectiveness of a Stepped-Care Approach to Long-Term Weight Loss (The Step-Up Study) (NCT00714168), a randomized na study. The primary outcome is Weight Loss.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00714168 |
| Phase | NA |
| Condition | Obesity |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 363 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University of Pittsburgh |
| Results posted | Yes |
2. Clinical Question
Population
Adults with obesity were eligible for a study of behavioral weight loss programs. The registry describes the population as people who are overweight or obese, and reports an enrollment of 363. Detailed eligibility criteria and the demographic composition of participants are not reported in the registry record.
Intervention
The stepped-care weight loss program used planned changes in the frequency of contact between participants and program staff at key times. The registry does not report the specific schedule, decision rules, or level of contact used in the program.
Comparator
The comparison was a standard behavioral weight loss program. The record identifies both programs as behavioral interventions, but does not describe their full content or how their contact schedules differed.
Primary question
The primary outcome was change in weight from baseline, measured at Month 18 and expressed in kg. The question was whether the two behavioral approaches differed in weight change at that time. Group-specific estimates are posted, but a direct between-group estimate and its uncertainty are not reported in the registry record.
3. Trial Design
The Step-Up Study was a randomized, parallel-group trial comparing two behavioral weight loss programs. One group took part in a standard behavioral weight loss program; the other took part in a stepped-care weight loss program. The registry lists the study as completed and reports an enrollment of 363. The sponsor was the University of Pittsburgh.
The registry lists the start as 2008-03 and primary completion as 2011-09. These dates describe the trial record and do not, by themselves, establish how long each participant was followed. The primary outcome was measured at Month 18. The registry does not report participant-level follow-up duration, retention by group, or the number of participants with an observed primary outcome.
Masking is listed as none. This indicates that the trial was not masked according to the registry entry; who knew each participant's assignment and whether outcome assessors were also unmasked are not described. The registry does not report the randomization sequence method, allocation concealment procedures, or stratification factors.
The primary analysis is described as intention-to-treat, with all randomized subjects included in the analysis. The posted group estimates are least-squares means with 95% confidence intervals. Details of the model used to obtain those adjusted means, including any covariates or handling of repeated measurements, are not reported in the registry record. The record lists four secondary outcomes: physical activity, energy intake, cardiovascular fitness, and body composition. Results for these outcomes are not reported in the information available in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: 433 individuals attended an orientation and provided written informed consent. Of these, 70 did not schedule a baseline assessment, failed to show for a baseline assessment, or were found to be ineligible after written consent was obtain. Thus, 363 were randomized to participate in this study.
Overall Study
| Stage | Standard Behavioral Weight Loss Program | Stepped-Care Weight Loss Program |
|---|---|---|
| STARTED | 165 | 198 |
| COMPLETED | 121 | 139 |
| NOT COMPLETED | 44 | 59 |
Reasons for not completing this period:
| Reason | Standard Behavioral Weight Loss Program | Stepped-Care Weight Loss Program |
|---|---|---|
| Pregnancy | 5 | 4 |
| Lost to Follow-up | 32 | 50 |
| Relocation | 4 | 3 |
| Non-study medical condition | 3 | 2 |
Analysis population for the primary outcome, as defined in the registry: We used an intention-to-treat analysis with all randomized subjects included in the analysis.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Standard Behavioral Weight Loss Program | Stepped-Care Weight Loss Program | Total |
|---|---|---|---|---|
| Participants analysed | 165 | 198 | 363 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 165 | 198 | 363 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | years | 42.39 (SD 9.22) | 42.04 (SD 8.89) | 42.20 (SD 9.03) |
| Sex: Female, Male: Female | Participants | 136 | 164 | 300 |
| Sex: Female, Male: Male | Participants | 29 | 34 | 63 |
| Region of Enrollment: United States | participants | 165 | 198 | 363 |
6. Primary Endpoint
The registry lists the primary outcome as Weight Loss, measured over Measured at Month 18.
| Element | Registry entry |
|---|---|
| Result type | Least Squares Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | kg |
| Endpoint classification | Continuous Endpoint |
The primary endpoint was change in weight from baseline, measured at Month 18 and expressed in kg. A negative change indicates that the estimated weight at follow-up was lower than baseline; a positive change would indicate an increase. This endpoint summarizes change over the period leading to the specified follow-up measurement, rather than weight at a single time point alone.
Weight is a continuous measure, so the result can be represented by a mean change and a confidence interval. The registry identifies the posted estimates as least-squares means. In general, a least-squares mean is an estimate derived from a statistical model; it may account for factors included in that model. Which factors and model terms were used is not reported in the registry record, so the estimates should not be described as adjusted for any particular characteristic.
Change from baseline is useful for describing how weight changed during follow-up in each study group. For the trial question, however, the key comparison is the difference in change between the randomized groups. Group-specific changes do not by themselves quantify that difference. Although the registry gives estimates and confidence intervals for both groups, it does not report a direct between-group estimate or its confidence interval.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
At Month 18, the posted least-squares mean change in weight was -8.1 kg in the standard behavioral weight loss group, with a 95% confidence interval from -9.4 to -6.9 kg. In the stepped-care group, the posted estimate was -6.9 kg, with a 95% confidence interval from -8.0 to -5.8 kg. Both group-specific point estimates describe a decrease from baseline. They are estimates of change within each group, not estimates of the comparative effect of one program versus the other.
The registry does not report the difference between the group estimates, a confidence interval for that difference, or a p-value for the primary comparison. Therefore, the posted information does not establish the precision of the contrast that directly addresses whether weight change differed between the programs. Comparing each group's estimate with zero is not the same as comparing the randomized groups with each other.
In general, a 95% confidence interval describes uncertainty around an estimate under the assumptions of the analysis. It is not a range containing every participant's weight change, and it does not give the probability that the true effect lies within that particular interval. Here, the intervals accompany the group-specific least-squares means. They should not be treated as the confidence interval for a between-group effect.
The record describes an intention-to-treat analysis including all randomized subjects. However, it does not provide the model specification or details of how missing outcome measurements were handled. Those details affect how the analysis should be understood, particularly if follow-up data were unavailable for some participants. The number with observed Month 18 measurements and the amount of missing data by group are not reported in the registry record.
The posted results support a description of the estimated average weight change in each group at the stated follow-up. They do not, on their own, provide a complete statistical test of the primary comparative question. No conclusion about the size or statistical precision of the between-group contrast should be drawn from the two separate estimates alone.
9. Statistical Methods Explained
What does a least-squares mean represent?
The primary results are identified as least-squares means. In general, this term refers to group estimates calculated from a statistical model, rather than necessarily being the raw arithmetic averages of observed measurements. The model can account for covariates or other features of the data if those terms are included. The registry does not report which covariates, model structure, or estimation details were used, so the posted estimates cannot be attributed to a specific adjustment.
The estimates describe change in weight from baseline at Month 18. The standard behavioral group estimate was -8.1 kg, and the stepped-care group estimate was -6.9 kg. Their respective 95% confidence intervals were -9.4 to -6.9 kg and -8.0 to -5.8 kg. These intervals convey uncertainty about each reported group estimate under the analysis assumptions. They do not describe the spread of individual participants' changes.
Why is a direct group comparison needed?
Random assignment sets up a comparison between the programs. The primary comparative question concerns how much the mean change differs between assigned groups. A direct estimate of that contrast, with its own uncertainty measure, is the clearest statistical summary of the randomized comparison. The registry record does not report that estimate or its confidence interval.
In general, separate confidence intervals for two groups cannot substitute for the confidence interval of their contrast. Their widths depend on uncertainty in each group estimate, while the uncertainty of a contrast also depends on how the estimates were obtained and, where relevant, their covariance. A reader should therefore not infer a formal between-group test from the two group-specific intervals. The direct comparison's p-value is also not reported in the registry record.
What does intention-to-treat mean?
The registry states that all randomized subjects were included in an intention-to-treat analysis. In general, intention-to-treat analysis aims to retain participants in the groups to which they were randomized, regardless of their later participation or adherence. This preserves the comparison defined by random assignment. The registry's statement identifies the intended analysis population, but does not explain how missing Month 18 measurements were incorporated or what assumptions were made about them.
Details such as imputation, likelihood-based handling of incomplete observations, or other missing-data methods are not reported in the registry record. These are examples of possible approaches, not claims about what this trial used. The number of participants with available outcome data, reasons for missingness, and any sensitivity analyses are also not reported.
How should confidence intervals be read?
In general, a confidence interval expresses the statistical uncertainty around an estimated quantity under a specified method and its assumptions. A narrower interval indicates greater precision than a wider interval for the same quantity and analysis context. The intervals posted for this trial apply to each group's least-squares mean change. They do not quantify uncertainty for a difference between programs.
A confidence interval is not a prediction interval for individual outcomes. It does not show the range of changes experienced by participants, and it does not imply that all participants had a change close to the group estimate. The registry does not post a measure of individual variation, such as a standard deviation, for the primary endpoint.
What do the planning assumptions say?
The registry's planning illustration is described as using the observed effect, equal allocation, a two-sided significance level of 0.05, and a normal approximation, with the target effect defined as a stated fraction of the observed effect. These are assumptions for a planning illustration, not evidence of the trial's original sample-size justification or analysis plan. The registry does not report the trial's own sample-size justification, or whether any interim analyses were planned or conducted. A planning calculation is not observed power and does not determine whether the posted results are precise enough for the comparative question.
Statistical significance, when reported, is only one part of interpretation. In general, estimates and confidence intervals help communicate both the direction and precision of a result. For this trial, the group-specific estimates are available, but the direct comparison and its uncertainty are not reported in the registry record. This limits the conclusions that can be drawn about the trial's primary comparative objective.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists four secondary outcomes: physical activity, energy intake, cardiovascular fitness, and body composition. It does not report results for these outcomes in the information available in the registry record. The approach to multiplicity—how the analysis would account for examining multiple outcomes or comparisons—is not reported in the registry record. No adjustment method or prespecified hierarchy of outcomes can be inferred from the list of outcomes alone.
The primary outcome is change in weight from baseline at Month 18. The record describes an intention-to-treat analysis with all randomized subjects included, but does not explain how missing Month 18 measurements were handled. It does not report the number of observed outcome measurements by group, reasons for missingness, imputation methods, or sensitivity analyses. The absence of these details makes it difficult to assess how assumptions about unavailable measurements may affect the estimates.
The statistical analysis plan, including the model specification and any planned interim analyses, is not reported in the registry record. The planning illustration's assumptions do not establish the analysis choices used for the trial's primary result. There is also no reported direct between-group estimate, confidence interval, or p-value for the primary comparison. These omissions matter separately: multiplicity concerns interpretation across analyses, missing-data methods concern incomplete observations, and the missing comparative estimate limits assessment of the principal randomized contrast.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Standard Behavioral Weight Loss Program | 0 | 165 | 0.0% |
| Stepped-Care Weight Loss Program | 0 | 198 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Standard Behavioral Weight Loss Program | 0 of 165 |
| Stepped-Care Weight Loss Program | 0 of 198 |
The registry reports zero serious adverse events among 165 participants at risk in the standard behavioral weight loss group and zero among 198 participants at risk in the stepped-care group. It also reports zero other adverse events among 165 participants at risk in the standard group and zero among 198 participants at risk in the stepped-care group. These figures describe the event counts recorded in the registry for the listed categories.
Zero recorded events does not establish that no health events occurred during the trial. The registry record does not report the definitions or collection procedures for these adverse event categories, the period of ascertainment, or whether all events were actively monitored. The deaths field is not reported for either group. The record also does not list serious adverse event terms. Safety figures should therefore be read as registry-reported counts, not as a complete account of all possible harms or as a comparison demonstrating that the programs have equivalent safety.
12. What the Result Does, and Does Not, Mean
The posted primary results describe estimated weight change from baseline at Month 18 in the two randomized groups. The standard behavioral program's least-squares mean change was -8.1 kg, with a 95% confidence interval from -9.4 to -6.9 kg. The stepped-care program's estimate was -6.9 kg, with a 95% confidence interval from -8.0 to -5.8 kg. These figures provide group-level descriptions of change and the uncertainty around each estimate.
The registry does not report a direct estimate of the difference between programs or the uncertainty around that difference. Consequently, the group-specific results do not establish whether the programs differed statistically, how precisely any difference was estimated, or what range of comparative effects is compatible with the posted analysis. A formal comparative conclusion requires the between-group result, not a comparison of separate point estimates alone.
The results also do not describe the distribution of individual responses. A group mean can coexist with variation among participants, and the registry does not report a measure of that variation for the primary outcome. The estimates should not be interpreted as the expected change for every participant.
The record identifies the analysis as intention-to-treat, but missing-data handling and model details are not reported. These gaps prevent a full assessment of the assumptions behind the estimates. The secondary outcomes are named, but their results are not reported in the registry record. The adverse event figures are limited to the listed registry counts and do not provide a full safety assessment.
In short, the posted results support a description of the Month 18 group-specific estimates. They do not supply the statistical contrast needed to answer the primary comparative question with a quantified estimate and precision. They should not be treated as a standalone basis for claims about the overall effectiveness or safety of either program.
13. Why This Trial Matters Statistically
This trial poses a common statistical question: how should a randomized comparison be interpreted when the registry posts estimates for each group but not the direct contrast between them? The group estimates describe change within each arm, but the scientific question concerns the difference between assigned approaches. Keeping those quantities distinct is essential to interpreting trial results.
The distinction matters because the uncertainty in a group mean is not the same as the uncertainty in a comparison. Separate group estimates and their confidence intervals cannot replace a reported contrast and its confidence interval. Without that direct result, readers cannot quantify the comparative effect or its precision from the registry record. This is true even when the study is randomized and the primary endpoint is clearly identified.
The registry also illustrates why analysis details are part of the evidence. Least-squares means are model-based estimates, but the model specification is not reported. The analysis is described as intention-to-treat, yet missing-data handling is not described. These statements provide useful context while leaving important questions about estimation and incomplete follow-up unresolved.
Finally, planning calculations and trial results answer different questions. The registry describes a planning illustration based on stated assumptions, but those assumptions are not the same as a documented trial design justification or an observed statistical result. Separating planning from inference, group-level change from between-group effect, and registry-reported counts from a full safety assessment helps readers avoid claims that the posted information cannot support.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The registry record does not report a direct between-group estimate for the primary outcome, its confidence interval, or its p-value. This is the main limitation for assessing the comparative objective. The posted group-specific least-squares means allow a description of change in each arm, but they do not quantify the primary contrast.
Details of the statistical model are not reported. The meaning of the least-squares estimates therefore cannot be tied to a specified set of covariate adjustments or other model assumptions. The record also does not report the number of participants with observed Month 18 weights, missing-data methods, reasons for missingness, or sensitivity analyses. Although the analysis is described as intention-to-treat, the handling of unavailable measurements remains unclear.
The study is listed as having no masking. The registry does not describe which roles were unmasked or whether outcome measurement procedures could have been affected. Randomization method and allocation concealment details are also not reported. These gaps do not establish that bias occurred; they limit assessment of the safeguards used.
Results for the four listed secondary outcomes are not reported in the registry record, and the approach to multiplicity is not reported. Safety information is limited to the posted event counts; event definitions and ascertainment details are not given, and deaths are not reported. These limitations restrict interpretation of both the broader outcome profile and the completeness of safety reporting.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Evaluating the Effectiveness of a Stepped-Care Approach to Long-Term Weight Loss (The Step-Up Study) — NCT00714168.
- Registry record last updated 2016-02-01; status last verified 2015-12.
- Results first posted 2016-02-01.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT00714168, the Step-Up Study, was a completed randomized, parallel-group trial sponsored by the University of Pittsburgh. It compared a standard behavioral weight loss program with a stepped-care weight loss program in people with obesity. Enrollment was 363, and masking was listed as none.
The primary outcome was change in weight from baseline, measured at Month 18. The registry reports least-squares mean changes of -8.1 kg for the standard program and -6.9 kg for stepped care, each with a 95% confidence interval. It does not report a direct between-group estimate or its uncertainty. The primary analysis is described as intention-to-treat, but model details and missing-data handling are not reported. Four secondary outcomes are listed, with no results reported in the registry record. Adverse event counts are zero in the listed categories for both groups; deaths are not reported.