J Manipulative Physiol Ther 2005 (Feb); 28 (2): 136–142 ~ FULL TEXT
Wenban AB, Nielsen MK
Australian Spinal Research Foundation
Objective: To report on a 26-year-old female patient presenting with uncomplicated chronic low back pain who received chiropractic maintenance care using 2 quality of life outcome assessment instruments.
Outcome measures: Short-form (SF-36) subscales, Quality of Well-Being Scale, Visual Analog Scale, and number of tender vetebral [sic] spinous processes.
Results: After 9 months of care the SF-36 subscale scores showed improvement. The SF-36, although low before care, approached normal on 3 subscales and exceeded normal population values on 5 subscales after 9 months. The SF-36 physical and mental composite scores improved from mean baseline scores of 23.4 and 25.3 to 43.7 and 62.8, respectively, after 9 months of care. The Quality of Well-Being Scale scores improved from a mean pre-intervention score of 1.1 to a post-intervention score of 8.2. The Visual Analog Scale scores improved from a mean pre-intervention score of 8 to a post-intervention score of 1.5. The mean number of chiropractic vertebral subluxations, detected via palpation of spinous process tenderness, went from a pre-care mean of 6.5 to a post-care mean of 4.
CONCLUSIONS: The patient appeared to experience improvement in quality of life while showing signs suggestive of improved spinal function. The relationship between indicators of vertebral subluxation and quality of life deserves further investigation using a research design that allows for exploration of possible causal relationships.
From the Full-Text Article:
This case represents an attempt to conceptualize and describe the ongoing chiropractic care of one patient from a broad, non–condition-specific, quality of life perspective. As opposed to describing the experiences of a sick person while under chiropractic care, this case study describes one patient's experience from a symptomatic state with poor quality of life to a nonsymptomatic state with a quality of life exceeding age-, sex-, and nationality-matched normative data on 5 of 8 SF-36 subscales. Furthermore, the patient's spinal function seems to have shown signs of improvement.
However, a number of limitations are inherent in this type of time-series case study. It needs to be noted that this case report, although prospective, documents the care delivered to only one patient. Therefore, the reader must take precautions to avoid drawing conclusions that risk the inherent limitations of this report. It should be remembered that this type of study is “concerned with and designed only to describe the existing distribution of variables without regard to causal or other hypotheses.”  In order for the present A/B time-series study, which is descriptive in nature, to take on the status of an experimental design, the case study would need to be extended to an A/B/A or A/B/A/B design. In this way, by repeatedly initiating and withdrawing the independent variable (ie, chiropractic spinal adjustment) while continuing to assess mediating variables (ie, subluxation indicators), and the dependent variable (ie, quality of life), it would strengthen the argument of a cause-effect relationship.
Because no withdrawal phase or subsequent follow-up period was included, we have no knowledge about the durability of the observed improvement in quality of life if the chiropractic care had ceased. It is possible that the patient's quality of life would have collapsed back down to baseline levels without chiropractic care. Alternatively, the gains in quality of life may have been sustained indefinitely even if chiropractic care was stopped after the 9 months of intervention. Again, to better understand the relationship between chiropractic MC and patient health, extended time-series case studies are recommended as one method by which we can better understand this relationship. It needs to be noted that the decision to pursue extended time-series studies, such as the A/B/A/B design, wherein care is withdrawn repeatedly, needs to be accompanied with the appropriate approval through an institutional review board or ethics review board.
A further limitation of this particular case study was that the baseline period during which quality of life, VAS scores, and information regarding subluxation indicators were collected was relatively short (4 weeks) compared with the length of the intervention phase of the study (9 months). The problem with having such a short baseline period is that long-term fluctuations in the natural history of an individual's quality of life may remain concealed. As one author  has recommended, taking at least 3 pre-intervention (baseline) measurements is required to make a tentative interpretation of level, trend, and variability. However, if our 3 baseline measurements are taken over too short a time frame we may know little more about longer-term fluctuations in the natural history of our mediating and dependent variables than if we only took one pre-intervention baseline measurement of each. As a result, the apparent improvement in quality of life seen across the course of this case study may have reflected long-term fluctuations in the natural history of this patient's quality of life as opposed to being caused by the chiropractic MC program.
Based on the comparison of baseline and post-intervention scores for the SF-36 questionnaire it is possible that ceiling effects may have been encountered. Ceiling effects occur when a questionnaire becomes unresponsive to change. Two of the SF-36 subscale scores (Social Function and Role Emotion) reached the maximum level possible, which may mean that some improvement in quality of life, may have gone undetected between the sixth and ninth months of care. Furthermore, in this particular patient, the SF-36 questionnaire did not appear to be as responsive to changes as was the QWBS early on in the present case study. As a result the SF-36 questionnaire and the QWBS might complement one another such that when used together they may allow a more responsive assessment of change across a broad range of health states than when used individually. It is recommended that the psychometric properties of the SF-36 questionnaire and QWBS receive further investigation among chiropractic patients in general, and chiropractic MC patients more specifically.
A further problem with interpreting changes in quality of life scores is that improved scores have been observed in patients participating in other studies who have been receiving placebo treatments and in patients in the run-in phase of studies before receiving either active or placebo interventions. 
It will be important to ask whether the improvements are a result of chiropractic spinal adjustments or some other aspect of MC, should further prospective studies show that there is an association between ongoing chiropractic MC, the resolution of subluxation indicators, and improved quality of life. For example, although an attempt was made to limit the independent variable of the chiropractic spinal adjustments, the patient was also exposed to a long-term chiropractor-patient relationship, educational material, reading matter, and an open plan environment. Any one of these, or other factors, may have contributed toward the observed changes in quality of life. Furthermore, the direction of the association cannot be assumed to be an improvement in quality of life following chiropractic MC. Although it may require extensive longitudinal studies to produce definitive answers to the nature of the relationship between quality of life, spinal function, and MC, some indication of the direction of the relationship might be obtained from cross-sectional studies comparing quality of life of chiropractic patients by length of time under chiropractic care.
We concur with the statement made by other authors11 that, “Overall, there is a tremendous need to research the hypothesis that regular maintenance chiropractic care will improve an individual's health status.” Furthermore, it is suggested that future attempts to research MC might best serve society's needs, while simultaneously reflecting the values ascribed to by practicing chiropractors, if such research is conceptualized within a non–condition-specific and quality of life model.
From a societal perspective, given that MC is recommended by many chiropractors, etching out an understanding of the experiences of large groups of relatively asymptomatic patients who are receiving ongoing chiropractic MC will be essential for appropriate resource allocation decisions and for future rational priority setting by chiropractic, third-party payers, and governmental bodies.
This prospective case report describes one patient's experience while participating in a chiropractic MC program. Although no causal associations can be made, she appears to have experienced an improvement in quality of life, as measured by 2 different quality of life instruments, while simultaneously experiencing an improvement in spinal function. This topic deserves further investigation with a research design that would allow exploration of causal relationships.