Basic Documentation of Adalimumab (Humira) in Patients With Ankylosing Spondylitis (AS): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Basic Documentation of Adalimumab (Humira) in Patients With Ankylosing Spondylitis (AS) (NCT01079182), a registered phase not stated study. The primary outcome is Mean Change From Baseline in Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) Score.

2. Clinical Question

3. Trial Design

This completed study is described as research on the safety and effectiveness of adalimumab in participants with ankylosing spondylitis in routine clinical practice in Germany. Enrollment is listed as 4681. The registry record gives a start date of 2006-01 and primary completion of 2014-05. AbbVie is listed as sponsor, with Abbott identified as the prior sponsor.

The record describes one group of participants with ankylosing spondylitis. It does not describe a randomized treatment allocation or a like-for-like control group; allocation is not stated. Consequently, the study information does not support interpreting the outcomes as a randomized comparison between adalimumab and another treatment or control condition. Routine-practice observations can describe measurements and events recorded among participants, but they do not by themselves separate treatment effects from changes over time or other influences.

The primary outcome is mean change from baseline in BASDAI, with measurement at baseline and at 3, 6, 9, 12, 18, and 24 months. Other listed outcomes include peripheral joint involvement, extraspinal manifestations, erythrocyte sedimentation rate, C-reactive protein, BAS-G, global assessment of disease activity, fatigue, and pain. The record lists 24 outcome measures overall.

The record identifies the primary analysis population as participants with adequate data available for evaluation of effectiveness. It does not state how adequacy was determined or provide the number included at each follow-up. It also lists zero analyses. The statistical analysis plan, details of follow-up and treatment exposure, and methods used to handle incomplete observations are not reported 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Full analysis set: Participants with adequate data available for evaluation of effectiveness.

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.

Population: A total of 4681 participants enrolled in the study, but the complete set of parameters was not available for each participant (Age and gender, N=4680; duration of AS symptoms, N=4521; HLA-B27 positive, N=3807).

6. Primary Endpoint

The registry lists the primary outcome as Mean Change From Baseline in Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) Score, measured over At Baseline (Month 0), 3, 6, 9, 12, 18, and 24 months.

The primary endpoint is mean change from baseline in BASDAI, a participant-reported measure of ankylosing spondylitis disease activity. Its questions cover fatigue, neck, back, or hip pain, peripheral joint swelling and pain, localized tenderness, and the severity and duration of morning stiffness. The score ranges from 0, meaning no symptoms, to 10, meaning severe symptoms. The registry record states that the minimum clinically important difference is 1.0.

The endpoint combines several symptom domains into one score, allowing disease activity to be summarized across follow-up visits. Change from baseline describes how the group’s average score differs from its starting measurement; it is not the same as an individual participant’s response. The registry record specifies mean change at baseline and follow-up through 24 months, but does not give the observed means or changes. It is therefore not possible to tell from the available record how large any change was, how variable it was, or whether it met the stated clinically important threshold.

The BASDAI calculation is described in the record, including the adjustment to the sixth question’s scale. The reported summary measure is a mean, with standard deviation specified as the dispersion measure. A mean can provide a compact description of group-level scores, while the standard deviation describes variation among scores; neither alone indicates the precision of the estimated mean. No confidence interval or other uncertainty estimate for the endpoint is reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record specifies a mean as the summary measure for the primary continuous outcome and a standard deviation as its dispersion measure. It does not report the numerical endpoint results or name the statistical method used to estimate or compare changes. The explanations below describe the general meaning of the listed methods and why the missing analysis details matter.

What does a mean change describe?

In general, a mean is the arithmetic average of the measurements included in an analysis. A mean change from baseline summarizes the average difference between follow-up scores and baseline scores for the participants whose data enter that analysis. It is a group-level summary: it does not show whether every participant changed in the same direction, nor does it describe the full distribution of individual changes.

For a repeated-measures outcome, the participants contributing data may differ across visits if observations are incomplete. The size and direction of a group mean can then reflect both changes in measurements and changes in the set of participants represented. The registry record defines the effectiveness population as participants with adequate data available, but does not report how many were included at each visit, how missing measurements were handled, or whether the same participants contributed throughout follow-up.

What does the standard deviation tell a reader?

In general, a standard deviation describes how spread out individual measurements are around their mean. A larger spread indicates greater variability among the measurements, while a smaller spread indicates that they are more concentrated around the mean. It is not the same as a confidence interval and does not by itself quantify the precision of the estimated mean. The registry record names standard deviation as the dispersion measure but does not provide its values for the primary endpoint.

A confidence interval, in general, expresses uncertainty around an estimate under the assumptions of the analysis. It helps readers assess which effect sizes are compatible with the data and model, rather than relying only on a point estimate. No confidence interval for BASDAI change is reported in the registry record. A p-value, in general, addresses the compatibility of data with a specified statistical null model; it does not measure clinical importance or establish causation. No primary endpoint p-value is reported.

How should the BASDAI scale be read?

The record defines BASDAI as a participant-reported score covering fatigue, pain, peripheral joint symptoms, tenderness, and morning stiffness. Its anchors are 0 for no symptoms and 10 for severe symptoms. It also states a minimum clinically important difference of 1.0. That threshold offers a clinical reference for judging the size of a change, but it is not a result. Without the observed mean change and its uncertainty, the record cannot show whether the endpoint crossed that threshold or how precisely any change was estimated.

The registry record describes a weighted calculation for the final BASDAI score and notes that the scale for the sixth question was reduced to 0–8 because that item was multiplied by 1.25. This explains how the endpoint was constructed; it does not provide the underlying observations or the analysis results.

What can planning calculations show?

In general, sample-size planning calculations estimate how many participants would be needed under specified assumptions to detect a chosen effect with a chosen statistical power. The planning assumptions associated with this study use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For non-time-to-event outcomes, the planning quantity is participants per arm. These are planning illustrations, not observed power and not evidence that the study was designed with those assumptions. The registry record does not report a design justification or an analysis plan, and the study is not described as a randomized two-arm comparison. Any such planning scenario should therefore be treated as hypothetical rather than as a description of the actual study design.

Over-dispersion is a general concern when observed variability exceeds what a statistical model assumes. If a model understates variability, uncertainty estimates can be too narrow and inferential results can appear more precise than warranted. The registry record does not identify a model for the primary endpoint or provide information to assess this issue. More generally, longitudinal clinical data require attention to within-participant correlation, changing follow-up, and incomplete measurements. The record does not state how these features were addressed.

Finally, statistical association and causal effect are different concepts. A within-group change can describe the observed course of measurements, while estimating a treatment effect requires a design and analysis that can support a comparison. Since no like-for-like control is described, the record does not permit a randomized treatment-effect interpretation. The sponsor’s statistical analysis and any reported estimates are not included in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 24 outcome measures, including BASDAI and several other measures of symptoms, disease activity, laboratory markers, and manifestations of ankylosing spondylitis. It lists zero analyses. The outcome list therefore shows the range of planned or recorded questions, but does not show which analyses were conducted, how they were prioritized, or what results they produced.

When many outcomes or repeated assessments are considered, the chance of finding an apparently unusual result by chance can increase. In general, multiplicity methods can address this concern, or an analysis plan can identify a primary outcome and distinguish it from secondary or exploratory questions. The analysis plan, any multiplicity adjustment, and any distinction between prespecified and post hoc analyses are not reported in the registry record. No conclusions about adjustment can be drawn from the listed outcomes alone.

The primary endpoint is specified at baseline and at 3, 6, 9, 12, 18, and 24 months. The registry record does not provide visit-specific participant counts, missing-data procedures, or a description of whether the analysis used all available observations or required complete follow-up. The full analysis set is defined as participants with adequate data available for evaluation of effectiveness, but the adequacy criteria and the number included are not reported. This prevents assessment of how the analysis population relates to enrollment or whether missing data could affect the estimated change.

These details matter because incomplete follow-up can affect both the representativeness and precision of longitudinal estimates. General methods for handling missing observations rely on assumptions, and the appropriate interpretation depends on which data are missing and why. Those patterns and assumptions are not reported in the registry record. The available information is insufficient to assess the handling of missingness or the robustness of the results.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: hospitalization (0.2%), pneumonia (0.1%), ankylosing spondylitis (0.1%), hip arthroplasty (0.1%), pyrexia (0.1%).

The registry record lists 141 participants as affected by serious adverse events among 4681 at risk, and 1099 as affected by other adverse events among 4681 at risk. These are registry counts, not comparative estimates. No deaths figure is reported in the registry record.

The most frequently listed serious-event terms are hospitalization (0.2%), pneumonia (0.1%), ankylosing spondylitis (0.1%), hip arthroplasty (0.1%), pyrexia (0.1%), and knee arthroplasty (0.1%). These percentages are presented as registry entries for the listed terms. They should not be added together: the record does not state whether participants could contribute more than one term, and the terms do not necessarily represent mutually exclusive groups.

These figures do not by themselves indicate whether an event was caused by adalimumab. The record does not provide a like-for-like control group, event timing, exposure-adjusted rates, or the method used to assess relatedness. The adverse-event counts are therefore descriptive registry information, not a comparative safety estimate. The absence of a deaths figure means that mortality cannot be characterized from the registry record.

12. What the Result Does, and Does Not, Mean

The record identifies a large routine-practice study of adalimumab in participants with ankylosing spondylitis and specifies a participant-reported disease activity measure for follow-up. It also lists adverse-event counts and a range of secondary outcomes. Those features show the kinds of outcomes the study sought to document in clinical practice, but they do not substitute for reported endpoint estimates.

The primary BASDAI outcome has a defined scale, a stated minimum clinically important difference of 1.0, and specified assessment times through 24 months. However, the registry record does not report the observed mean changes or their uncertainty. It therefore does not show the size or direction of change, whether the mean change met the stated threshold, or how precisely a change was estimated. The outcome description alone is not evidence that effectiveness was maintained.

The study is not described as a randomized comparison, and the record does not identify a like-for-like control group. As a general statistical principle, a before-and-after pattern in one group cannot distinguish a treatment effect from other changes occurring over time. Routine-practice observations may be relevant to describing care outside a tightly controlled comparison, but causal interpretation depends on design, measurement, and analysis details that are not reported.

The adverse-event figures likewise describe recorded events rather than their causes. Without comparative information or details about timing, exposure, and event assessment, they cannot establish whether adalimumab increased or reduced risk. The registry record also does not report a deaths figure.

Accordingly, the record supports a description of the study question, outcome definitions, follow-up schedule, and selected safety counts. It does not support a conclusion about the magnitude or precision of effectiveness, a causal treatment effect, or comparative safety. These limits arise from the results and analysis information not reported in the registry record, not from the BASDAI scale itself.

13. Why This Trial Matters Statistically

This study illustrates the statistical distinction between documenting outcomes in routine clinical practice and estimating a treatment effect through a controlled comparison. A registry record can identify a substantial study population, specify outcome measures, and describe follow-up without providing enough information to determine the magnitude or precision of the observed outcomes. Readers need both endpoint definitions and numerical estimates to judge what the data show.

The primary measure is a participant-reported composite covering several symptom domains. Specifying its scoring method, scale anchors, and minimum clinically important difference helps clarify what the outcome is intended to represent. Yet those definitions cannot answer whether scores changed, whether a change was clinically important, or how much uncertainty surrounded it. This is why reported estimates and uncertainty measures are essential alongside outcome descriptions.

The record also underscores the importance of analysis-population and missing-data details in long-term follow-up. Measurements at scheduled visits can represent different sets of participants if observations are incomplete. Without visit-specific counts and an explicit missing-data approach, it is difficult to assess whether the reported trajectory would represent the enrolled group or those with available measurements.

Finally, the record lists many outcomes but no analyses. That gap makes it impossible to distinguish the primary result from secondary findings or assess how multiple outcomes were handled. More complete reporting of analyses, estimates, uncertainty, and population flow would allow readers to evaluate both the strength and the limits of the evidence. In its current form, the registry entry is informative about the study’s aims and measurement framework, while the missing results constrain statistical interpretation.

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 most important trial-specific limitation for interpretation is the absence of numerical primary endpoint results in the registry record. Although the endpoint, assessment schedule, and dispersion measure are defined, the record does not report the mean changes, standard deviations, confidence intervals, or test results. This prevents evaluation of the effect’s size, direction, precision, or relation to the stated minimum clinically important difference.

The study is described as routine clinical practice in Germany, but the registry record does not provide details on participant characteristics, treatment duration for individual participants, adherence, concomitant care, or follow-up completeness. These omissions limit understanding of who contributed to the outcome estimates and how representative those observations may be. The record defines an effectiveness population based on adequate available data but does not describe the criteria or its size.

No randomized, like-for-like control comparison is described. This limits causal interpretation of any change over time and makes it difficult to separate treatment-related changes from other influences. The record also does not report the statistical analysis plan, modeling approach, handling of repeated measurements, or missing-data methods.

Although 24 outcome measures are listed, zero analyses are listed. The record does not explain which outcomes were analyzed, whether analyses followed a prespecified plan, or whether multiplicity was addressed. Safety reporting is also limited: event counts and selected serious-event terms are listed, but details on timing, exposure, relatedness, and comparative rates are not. A deaths figure is not reported in the registry record. These gaps make the entry more useful for understanding study aims and measurement than for evaluating efficacy or comparative safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Basic Documentation of Adalimumab (Humira) in Patients With Ankylosing Spondylitis (AS) — NCT01079182.
• Registry record last updated 2015-07-09; status last verified 2015-06.
• Results first posted 2015-06-01.
• 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.

18. Record Summary

The completed study, NCT01079182, concerns adalimumab in participants with ankylosing spondylitis in routine clinical practice in Germany. Enrollment is listed as 4681; the record gives a start date of 2006-01 and primary completion of 2014-05. AbbVie is listed as sponsor, with Abbott as prior sponsor.

The primary outcome is mean change from baseline in BASDAI, assessed at baseline and at follow-up through 24 months. The registry record lists 24 outcome measures and zero analyses. It describes one group and does not identify a like-for-like randomized comparator. Numerical primary endpoint results and their uncertainty are not reported in the registry record.

Safety entries list 141 participants affected by serious adverse events and 1099 affected by other adverse events, with 4681 at risk for each category. Selected serious-event terms and percentages are reported, but the record does not provide a deaths figure. Overall, the entry documents the study question, outcome definitions, and selected event counts while leaving the effectiveness estimates and analysis details unavailable.