Patient Response to Spinal Manipulation - Pilot Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Patient Response to Spinal Manipulation - Pilot Study (NCT01562756), a na na study. The primary outcome is Feasibility of Conducting a Full-scale Randomized Control Trial to Evaluate Patient Response to Spinal Manipulation: Number of Participants Who Were Recruited, Consented, Enrolled, and Completed the Study.

2. Clinical Question

This is not an efficacy question about whether spinal manipulation changes low back pain. The stated purpose was preparatory: assess whether study procedures and data collection could be put in place ahead of a full-scale trial. The primary outcome was defined in terms of participant flow and retention, rather than a comparison of clinical outcomes between treatment groups.

The planned observation period was approximately 4-6 weeks, including initial eligibility screening, baseline visits, and 2 weeks of treatment visits. That timeframe describes the outcome-measure period in the registry record; it does not establish that every participant followed the same schedule or completed every visit. The record does not report participant-level timelines or the number completing the study.

For a reader considering the clinical question, the key distinction is between a feasibility objective and a treatment-effect objective. A feasibility pilot can identify practical questions for a later trial, but the record does not give the recruitment and retention counts needed to quantify those aspects. Nor does it provide comparative clinical outcome results that would answer whether treatment changed symptoms.

3. Trial Design

The registry record describes the study as a pilot for Patient Response to Spinal Manipulation (PRiSM). Palmer College of Chiropractic is listed as sponsor, and the brief summary describes collaboration with the University of Iowa. The stated purpose was testing equipment, finalizing the data collection protocol, and training study personnel in preparation for a full-scale trial.

The design is recorded as single group, with allocation listed as NA and masking as none. One intervention is listed: HVLA-SM, described as high velocity, low amplitude lumbo-pelvic manipulation. There is no listed control intervention or comparator group. Consequently, the record does not support a randomized, between-group treatment comparison. The study should be understood as a feasibility pilot, not as a controlled efficacy trial.

Enrollment is reported as 6. The study status is completed, with a start date of 2012-02 and a primary completion date of 2012-05. The phase is recorded as NA. Further protocol details, including a more complete account of eligibility criteria, the schedule of procedures, and any deviations from the intended procedures, are not reported in the registry record.

The primary outcome was the number of participants recruited, consented, enrolled, and retained. Its timeframe is described as approximately 4-6 weeks, covering screening, baseline visits, and 2 weeks of treatment visits. Although the registry record describes the intended feasibility measures, it does not provide their observed counts. The record lists 2 outcome measures but does not provide details about the other measure.

The record lists 0 analyses. It does not report an analysis plan, methods for handling incomplete observations, or a sample-size justification for this pilot. The study's stated purpose offers context for its design, but does not fill in those missing methods or outcome details. A small single-group pilot can inform preparation for later work, but it cannot isolate an intervention effect from changes that could occur without a comparator.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Feasibility of Conducting a Full-scale Randomized Control Trial to Evaluate Patient Response to Spinal Manipulation: Number of Participants Who Were Recruited, Consented, Enrolled, and Completed the Study, measured over Approximately 4-6 weeks including initial eligibility screening, baseline visits, and 2 weeks of treatment visits.

The primary endpoint was a set of participant counts: the numbers recruited, consented, enrolled, and retained through the study. These measures describe different points in the path from approaching potential participants to keeping enrolled participants involved through follow-up. Together, they are intended to help assess whether the practical steps needed for a future trial can be carried out.

Feasibility outcomes are used in pilot research because the immediate question may be whether the study procedures can be implemented, rather than whether an intervention changes a clinical outcome. Recruitment and consent counts can describe whether participants enter the study process; enrollment and retention counts can describe subsequent participation. These counts can help inform planning, but interpretation depends on having the actual results and clear definitions for each stage.

The registry record states that feasibility was measured by these participant numbers and gives an approximate 4-6 week timeframe, including initial eligibility screening, baseline visits, and 2 weeks of treatment visits. It reports 6 enrolled participants, but does not report the separate counts recruited, consented, or retained, or the number who completed the study. The enrollment figure alone therefore does not supply the complete primary endpoint result.

Because the endpoint is participant flow rather than a comparative clinical response, it does not measure whether spinal manipulation improved low back pain. The record does not give a treatment-versus-control contrast, and it does not provide enough reported endpoint detail to quantify the feasibility findings beyond enrollment.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical methods that can be interpreted are constrained by the detail in the registry record. The design is listed as single group, allocation as NA, masking as none, and the number of analyses as 0. The primary endpoint is described as participant counts for recruitment, consent, enrollment, and retention. The record does not report an analysis plan, an inferential model, or estimates for those separate counts.

What can a participant count show?

As a general statistical concept, counts describe how many observations fall into a category. For a feasibility study, the relevant categories may be stages such as recruited, consented, enrolled, or retained. Each count answers a practical question, but its meaning depends on a clearly defined denominator and on the rules used to assign participants to each stage. The registry record names these stages but does not give their observed counts or describe all of their operational definitions.

The record reports 6 enrolled participants. That is a descriptive count, not an estimate of a treatment effect. It also does not provide the number approached or eligible, so it cannot be used to infer a recruitment rate. Rates require both a numerator and a denominator defined for the relevant process; the registry record does not report the needed figures for the recruitment and retention stages.

Why does the single-group design matter?

In general, a controlled comparison helps distinguish changes associated with an intervention from changes that may occur over time or for other reasons. This study lists one intervention and no comparator group. It therefore cannot estimate a between-group contrast. The lack of a comparator is consistent with the stated pilot and feasibility purpose, but it limits interpretation of any clinical outcome as an intervention effect.

The registry record does not report a model or statistical test for clinical outcomes. Because the record lists 0 analyses, no adjusted or unadjusted treatment-effect results can be interpreted. It would not be appropriate to infer a clinical effect from the design description, enrollment number, or safety counts.

What does an unreported analysis plan mean?

An analysis plan usually specifies how outcomes will be summarized, which statistical methods will be used, and how incomplete observations or other complications will be handled. These details matter because different methods can answer different questions and rely on different assumptions. The analysis plan and handling of missing data are not reported in the registry record. The registry record also does not report interim analyses or a sample-size justification.

In general, over-dispersion occurs when count variability is greater than a statistical model expects. When present, it can make standard errors and uncertainty estimates from a model too small if the extra variability is ignored. The record does not identify a count model or provide data to assess over-dispersion; this concept is relevant only as a general consideration, not as a finding about this pilot.

How should planning illustrations be read?

In general, sample-size planning asks how many participants may be needed to detect an assumed effect under stated statistical conditions. A planning illustration is conditional on those assumptions, including the chosen effect to detect, the significance level, the allocation structure, and the calculation method. It is not a result observed in the trial and is not evidence that a study had a particular probability of detecting an effect. The planning assumptions associated with the record specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those are assumptions for an illustration, not descriptions of this single-group pilot's allocation.

The record does not report a treatment-effect estimate from which to assess a clinical contrast, and no numerical planning estimate is stated in the registry entries. Any planning illustration should therefore be kept separate from observed study findings. Sample-size calculations are planning tools, not observed power. The registry record does not report a formal sample-size justification for this pilot.

In general, a confidence interval conveys uncertainty around an estimate, while a p-value describes the compatibility of data with a specified null hypothesis under a statistical model. Neither can be interpreted without the relevant estimate, analysis, and assumptions. The registry record reports no p-values or confidence intervals for this study. The absence of those results is not a statistical demonstration that an effect is absent; it means no such analysis is reported for interpretation.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 2 outcome measures and identifies the feasibility count as the primary outcome. It lists 0 analyses. No statistical analysis plan, list of planned hypothesis tests, or strategy for accounting for multiple comparisons is reported in the registry record. Without those details or reported analyses, it is not possible to assess whether multiplicity was relevant to any inferential findings or how it might have been handled.

Missing-data methods are also not reported in the registry record. The primary endpoint includes recruitment, consent, enrollment, and retention counts, but the separate observed values are not reported apart from enrollment. The record does not say whether any participants had incomplete visits, how incomplete information was classified, or how such information would be handled in an analysis. The completion count is not reported.

The analysis populations are not described. The registry record does not state whether analyses were planned for all enrolled participants, only participants completing specified visits, or another defined group. Because the study is listed as single group and no analyses are listed, there are no reported analysis populations or population-specific estimates to compare.

These omissions do not establish that missing data or multiplicity problems occurred. They mean that the registry record does not give the information needed to evaluate those issues. For a feasibility outcome, clear definitions of the participant stages and the counts at each stage are particularly important to interpreting recruitment and retention.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The registry record lists safety counts for the HVLA-SM group. It reports 0 participants with a serious adverse event among 6 at risk, 0 participants with another adverse event among 6 at risk, and 0 deaths among 6 at risk. No serious adverse-event terms are listed.

These figures should be read as the event counts recorded for this study, not as proof that the intervention has no safety risks. The study enrolled 6 participants, and a small pilot provides limited information about uncommon events. The registry record does not provide event narratives, collection procedures, follow-up completeness, or further details about how adverse events were classified. The counts also do not come from a comparative safety assessment because no comparator group is listed.

In general, an observed count of zero means that no events of that category are recorded in the reported data; it does not establish that the underlying risk is zero. The posted counts are descriptive and should not be extended beyond this study's participants and reporting. They do not answer whether event rates differ from those under another treatment or no treatment.

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

The result that can be stated directly is that the registry record reports 6 enrolled participants in a completed, single-group pilot study of HVLA-SM. The stated purpose was to test equipment, finalize data collection procedures, and train study personnel before a full-scale trial. The primary feasibility outcome was defined around recruitment, consent, enrollment, and retention.

The record does not report the observed counts for recruited, consented, or retained participants, or the number who completed the study. Therefore, it does not provide enough information to quantify those aspects of feasibility. Enrollment is one part of the defined outcome, not a substitute for the complete set of participant-flow results.

The design does not include a listed comparator or randomized allocation. The record reports no outcome analyses, clinical treatment-effect estimate, confidence interval, or p-value. Accordingly, it does not show whether spinal manipulation changed low back pain, and it cannot establish that it did or did not have a clinical effect. A pilot's stated preparation goals should not be treated as evidence about efficacy.

The registry record lists zero serious adverse events, zero other adverse events, and zero deaths among 6 participants at risk in the HVLA-SM group. These are descriptive safety figures for the participants and reporting captured by the record. They are not a comparison with another group and do not demonstrate that the risk of an event is absent.

In general, absence of a reported analysis is different from a result showing no difference. The former leaves a question unanswered; the latter would require an analysis and an estimate with uncertainty. The record supports a narrow description of the study's purpose, design, enrollment, and listed event counts. It does not support conclusions about a treatment effect or the complete success of recruitment and retention procedures.

13. Why This Trial Matters Statistically

This study matters statistically because it illustrates the distinction between feasibility outcomes and clinical treatment effects. A pilot can be designed to test whether equipment, data collection, and study procedures are ready for a larger trial. Those goals require descriptive information about participant flow and completion, rather than necessarily a comparison of clinical outcomes between groups.

The stated primary endpoint is well aligned with that preparatory purpose: counts of people recruited, consented, enrolled, and retained. But the registry record reports only the enrollment count, not the separate values for the other stages. That gap shows why a clear endpoint definition alone is not enough for interpretation; the observed values and the definitions of the stages are also needed.

The single-group design is another important statistical feature. It fits a pilot focused on procedures, but it does not supply a randomized comparator. As a result, it cannot separate a treatment effect from changes over time or other influences. A later efficacy question would require a design and analysis capable of making a relevant comparison, with its methods described in the registry record or trial report.

The record also demonstrates why safety counts require context. Zero recorded events in a small pilot is a descriptive observation, not evidence that risk is absent. Similarly, no reported analyses do not establish no effect. Statistical interpretation depends on what was measured, the design used, the analysis performed, and the precision of the resulting estimates. Several of those elements are not reported in this registry record.

For researchers planning subsequent work, the study's stated purpose is to prepare for a full-scale trial. The registry record, however, does not provide recruitment and retention results or a sample-size justification that could be used to evaluate planning decisions. Its value in the available record is therefore primarily in clarifying the pilot's intended role and highlighting which feasibility and analysis details remain unavailable.

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 main limitation for interpreting feasibility is that the registry record does not report the separate counts for participants recruited, consented, or retained, or the number who completed the study. Although enrollment is reported as 6, the other participant-flow measures named in the primary endpoint cannot be assessed. Recruitment and retention performance therefore cannot be quantified from the record.

The study is listed as single group, with allocation recorded as NA, masking as none, and no comparator group described. This design does not support a randomized comparison or a causal estimate of an intervention effect. The record also lists 0 analyses, so no clinical outcome estimate, uncertainty interval, or hypothesis test is available.

Further protocol and analysis detail is not reported in the registry record. This includes a statistical analysis plan, methods for incomplete observations, definitions of analysis populations, interim analyses, and a sample-size justification. The record lists 2 outcome measures, but the second measure is not described in the details available. These omissions limit assessment of how outcomes were intended to be collected and analyzed.

The safety information is limited to counts: zero serious adverse events, zero other adverse events, and zero deaths among 6 participants at risk in the HVLA-SM group. The record does not provide event descriptions or additional information on ascertainment and classification. The absence of a comparator also prevents a comparative safety interpretation.

Finally, the registry record's stated pilot purpose concerns preparation for a full-scale trial. The information available does not show whether each preparatory aim was met or whether the study's procedures were changed in response to experience. These limits should be kept distinct from findings: missing reporting does not establish that a procedure failed, that data were incomplete, or that an effect was absent.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Patient Response to Spinal Manipulation - Pilot Study — NCT01562756.
• Registry record last updated 2017-07-31; status last verified 2017-05.
• Results first posted 2017-07-31.
• 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 registry record describes NCT01562756, Patient Response to Spinal Manipulation - Pilot Study, also titled Pilot for Patient Response to Spinal Manipulation (PRiSM). Palmer College of Chiropractic is listed as sponsor, with collaboration with the University of Iowa noted in the brief summary. The study is completed, with a start date of 2012-02 and primary completion date of 2012-05.

The design is single group, with no masking and allocation recorded as NA. The listed intervention is high velocity, low amplitude lumbo-pelvic manipulation. Enrollment is 6, and low back pain is the listed condition. The primary outcome concerns participant counts for recruitment, consent, enrollment, and retention over approximately 4-6 weeks, including 2 weeks of treatment visits.

The record lists 2 outcome measures and 0 analyses. It does not report most primary feasibility counts or a clinical treatment-effect analysis. For the HVLA-SM group, the registry record lists 0 serious adverse events, 0 other adverse events, and 0 deaths among 6 at risk. The available results are descriptive and do not establish a comparative treatment effect.