the headache symptom questionnaire: discriminant classificatory ability and headache syndromes...

Journal o f Behavioral Assessment, Vol. 4, No. 1, 1982

The Headache Symptom Questionnaire: Discriminant Classificatory Ability and Headache Syndromes Suggested by a Factor Analysis

John G. Arena, t Edward B. Blanchard, 1.2 Frank Andrasik, 1 and Bruce C. Dudek I

Accepted for publication: October 10, 1981

A brief Headache Symptom Questionnaire was administered to 129 chronic headache Sufferers. The questionnaire accurately classified 68.42% of headache subjects in their proper diagnostic category, comparabl e to, but statistically less accurate than, the 86.4% agreement between expert headache diagnosticians using clinical interviews. Results o f a factor analysis o f the Headache Symptom Questionnaire lend support for their being two commonly accepted global headache categories-vascular/migraine and muscle contraction-and one headache dimension concerned with duration o f headache pain. Combined migraine-muscle contraction headache was found to be related more to migraine than to muscle contraction headache, and cluster headaches emerged as a separate clinical entity, not loading positively on any factor and loading negatively on all three.

KEY WORDS: Headache Symptoms Questionnaire; diagnosis; factor analysis.

This research was supported in part by Grant NS-15235 from the National Institute of Neurological and Commurlicative Disorders and Stroke. ~SUNYA Headache Project, State University of New York at Albany, Albany, New York 12203.

2To whom correspondence should be addressed at SUNYA Headache Project, 107 Draper Hall, 135 Western Avenue, Albany, New York 12203.

55

o164-o3o5/82/0300-oo555o3.oo/o © 1982 Plenum Publishing Corporation

56 Arena, Blanchard, Andrasik, and Dudek

INTRODUCTION

Accurate and reliable diagnosis is the keystone of both good clinical care and good clinical research. An area of much interest to behavioral clinicians in recent years has been the assessment and treatment of chronic headache (Blachard et al., 1979). The diagnosis of headache type is generally accomplished by a clinical interview emphasizing headache history and, much less frequently, by a physical and neurological examination. The latter are often not available to the nonphysician behaviorist. In addition, unless the interview is standardized, there are many potential sources of error; such error could arise due to the failure of the interviewer to ask certain key questions, through interviewer bias, or because of a misunderstanding of a particular question on the part of the interviewee (Hay et al., 1979; Haynes and Jensen, 1979; Russo et al., 1980). A standardized clinical interview for headache history, which we have shown in previous work (Blanchard et al., 1981) to be reliable in approximately 86% of patients, requires 45-90 min. In this paper we report on the classificatory ability of a brief paper-and-pencil Headache Symptom Questionnaire.

An additional function of this paper is to examine, through multivariate statistical procedures, the validity of standard headache diagnoses. There have been two previous factor analytic studies of the symptoms of headache patients. The first, by Barrie et al., (1968), employed a population of 65 migraineurs and combined migraine-muscle contraction headache suffers. The investigators had their patients self-monitor each headache occurrence and entered six of the variables (mean severity score, percentage of bilateral attacks, percentage of attacks with photophobia, percentage of attacks with scotoma or teichopsia, percentage of attacks with vomitting, and mean duration of attacks) in a principal-component factor analysis. They arrived at only one factor, on which percentage of bilateral attacks did not load and all other variables loaded evenly, which they termed a general distress factor. Perhaps their small number of variables and their use of patients from only two headache types precluded any other meaningful factors emerging.

A second factor analytic investigation was conducted by Ziegler et al. (1972). They administered to 289 migraine and nonmigraine headache sufferers a paper-and-pencil questionnaire from which 27 predominantly dichotomous variables were constructed and subjected these to a principal components factor analysis. Among their conclusions were: (1) since three factors rather than one were extracted that fitted their migraine headache patients, current definitions of migraine may be incongruent with the reality of patient symptomatology (i.e., there are at least three different types of migraine); (2) cluster headache individuals are quite similar to migraineurs;

The Headache Symptom Questionnaire 57

and (3) a factor which they termed a tension headache factor did not contain neck pain or stress related loadings; rather it was associated with headache duration. On the basis of this, and other research (Couch et aL, 1975; Ziegler, 1979; Ziegler et aL, 1978), Ziegler has concluded that standard headache diagnostic groupings are inappropriate.

There are a number of methodological shortcomings in the paper by Ziegler et aL (1972), however. Their use of dichotomous variables assumes that a variable is mutually exclusive and exhaustive. Many headache symptoms, however, (e.g., headaches brought on by stress, unilateral pain, and prodroma! symptoms) are not typically present at every headache occurrence (Adams et al., 1980; Barrie et aL, 1968; Waters, 1971). Forcing an individual to choose "yes" or "no" to an item creates an artificial dichotomy resulting in greater error variance than allowing multiple responses along a continuum for each item (Comrey, 1978). Also, Ziegler et aL (1972) did not present any inclusion criteria for their headache diagnoses or specific diagnostic assignment for approximately one-half of the sample; the reader is told only that there are 160 migraineurs and 129 nonmigraineurs. In addition, many features that others have used for excluding subjects in headache research, such as the presence of a severe psychiatric disorder, intellectual deficit, or significant neurological abnormalities, were not employed by Ziegler et al. (1972). This paper attempts to replicate the results of Ziegler et al. (1972) correcting for the above methodological problems.

METHOD

Subjects

Subjects consisted of 129 consecutive patients complaining of chronic, severe headaches who presented to a research clinic concerned with the psychological treatment of headaches. There were 32 migraineurs, 27 combined migraine-muscle contraction headache suffers, 57 muscle contraction headache suffers, and 13 cluster headache individuals. Every headache sufferer was independently interviewed and diagnosed by two diagnosticians: one a doctoral student in clinical psychology, the other a board-certified neurologist. Diagnostic disagreements were solved by a conference between the two diagnosticians. Previous analyses have shown there to be an 86.4% exact agreement between these two sets of diagnosticians [Cohen's x =" 0.799, p < 0.0001 (Blanchard et al., 1981)]. Diagnoses were based on the criteria developed by the Ad Hoc Committee


Table I. Age, Gioup and Sex Distribution of Study Participants

Muscle Migraine Combined contraction Cluster

Age (years) Mean 39.5 36.3 40.8 44.2 SD 12.4 10.0 14.1 11.2 Range 20-64 23 -65 18 -6 8 26 -61

Number of males 6 1 11 9

Number of females 26 26 46 4

on Classification of Headache (1962) and by information reported by Diamond and Dalessio (1978). The specific inclusion and exclusion criteria for each headache type have been described elsewhere (Andrasik et al., 1982).

Table I presents the sex and age distribution of the study participants.

Headache Symptom Questionnaire

The Headache Symptom Questionnaire was originally developed by Epstein and Abel (1977) to obtain systematic self-report of 16 headache symptoms as an aid in the diagnosis and treatment of migraine, combined migraine-muscle contraction, and muscle contraction headache (see Table II for a listing of the items). Each item is scored from 0 to 4 (never, infre- quently, sometimes, usually, always). The Headache Symptom Ques- tionnaire was included as part of a larger psychological testing battery. Headache participants completed the battery as a prerequisite to entering a treatment program.

RESULTS

Factor Analysis of the Headache Symptom Questionnaire

The 16 items from the Headache Symptom Questionnaire were factor analyzed by a principal-factor solution with squared multiple correlations on the diagonals followed by a varimax rotation of those factors with eigenvalues greater than or equal to one 3 (Nie et al., 1975). An item was

3The initial factor correlation matrix is available upon request from Edward B. Blanchard.


considered to load significantly on a factor if that item was equal to or greater than the absolute value of 0.30 on that factor (Child, 1970).

The results of the factor analysis yielded an interpretable three-factor structure, which accounted for 74.8% of the common variance. Table II presents the individual item descriptions, the response frequencies, the factor loadings for each of the three factors, as well as the chi-square values and probabilities for each item of the Headache Symptom Questionnaire. To assure against spurious findings, a minimum significance level of 0.01 was decided upon for all multiple analyses in this paper, with 0.05 to 0.015 being a nonsignificant trend.

Factor 1, which accounted for 3213% of the common variance, had significant loading on five items: 4 7, 11, 9, 10, and 5. This factor, with its loadings emphasizing unilateral pain, prodromal symptoms, nausea and/or vomiting, and throbbing/pulsating pain, appears to be a vascular/ migraine factor.

Factor 2, accounting for 25.2% of the common variance, also had significant factor loadings on five item: items 16, 15, 4, 8, and 6. This factor, with its loadings emphasizing stress-related headache etiology, pain worse at the end of the working day, neck and shoulder pain, as well as a band or caplike pressure, seems to be a muscle contraction headache factor.

Factor 3, which accounted for 17.3 % of the common variance, had significant factor loadings on 3 of the 16 items: 2, 1, and 5. This factor is less clear than the previous two, but does seem to be tapping into a headache duration dimension with its emphasis on awakening with headaches that last over 24 hr.

It is interesting to note that four items of the Headache Symptom Questionnaire did not load significantly on any of the three factors: Items 3, 12, 13, and 14. Two of these (items 13 and 14) relate to medication use. Apparently, medication use does not account for much of the variance in our sample. It is also interesting to note that the discriminant analysis (see below) did not employ these two items as discriminating variables.

In an attempt to clarify the above factors, factor scores for each factor were created for every patient. The factor scores were obtained by multiplying the standard scores for the original variables by the factor score coefficients, resulting in Standardized scores for each factor, with a mean of 0 and a standard deviation of 1. A mean split (Barrie et al., 1968) was performed and the percentage of cases in each diagnostic group loading positively or negatively on each of the three factors was then determined. Chi-square analyses of the form 2 (loading positively/negatively on that

4Item numbers refer to ,the order of the items in the questionnaire as it was given to participants.


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Table IlL Factor Loadings by Diagnostic Groups

Muscle Chi-square Migraine Combined contraction Cluster Chi-squaze probability

Factor 1 30.0 0.0000 Positive

N 22 22 14 6 % 68.8 81.5 24.6 46.2

Negative N 10 5 43 7 % 31.3 18.5 75.4 53.8

Factor 2 Positive

N 11 18 33 1 % 34.4 66.7 57.9 7.7

Negative N 21 9 24 12 % 65.6 33.3 42.1 92.3

Factor 3 Positive

N 13 15 28 1 % 40.6 55.6 49.1 7.7

Negative N 19 12 29 12 % 59.4 44.4 50.9 92.3

16.8 0.0008

9.2 0.0272

factor) x 4 (headache diagnostic group) were significant or a nonsignificant trend for all three analyses.

Table I I I presents the percentages o f each diagnostic group loading on each factor and the chi-square values and probabilities for each. Examinat ion of these diagnostic percentages in Table I I I reveal five findings of interest: (1) factor 1 appears to be a vascular /migraine factor; (2) factor 2 does appear to be a muscle-contract ion headache factor; (3) combined migraine-muscle contraction headache loads on both the above factors but is more closely related to the vascular /migraine factor; (4) cluster headaches do not load sizably on any factor in a positive direction; and (5) there seems to be little difference among migraine, muscle contraction, and combined migraine-muscle contraction headache on factor 3, with cluster headache overwhelmingly loading negative (92.3 %).

Discriminant Ability of the Headache Symptom Questionnaire

To determine the predictive diagnostic power of the 16 items contained in the Headache Symptom Questionnaire, a stepwise discriminant analyses (Nie et ai., 1975) was performed. The stepwise analysis computed linear discriminant functions on each of the 16


Table IV. Prediction Results a

Predicted group membership

Actual Number group of Muscle

membership cases Migraine Combined contraction Cluster

Migraine 26 14 7. 3 2 53.8% 26.9% 11.5% 7.7%

Combined 26 6 17 3 0 23.1% 65.4% 11.5% 0.0%

Muscle contraction 51 1 18 39 3 2.0% 15.7% 76.5% 5.9%

Cluster 11 2 1 0 8 18.2% 9.1% 0.0% 72.7%

Total 114

apercentage of cases correctly classified: 68.42%.

Table V. Classification Function Coefficients (Fischer's Linear Dis- criminant Functions)a

Diagnostic group

Discriminating Muscle variable Migraine Combined contraction Cluster

Item 1 1.439 1.507 2.481 1.465 Item 3 0.851 0.899 0.973 2.030 Item 4 1.672 1.670 2.115 0.922 Item 6 1.619 1.517 1.774 0.940 Item 7 2.137 1.869 1.343 2.782 Item 8 0.361 0.479 0.069 -0 .583 Item 9 -0.221 -0 .088 -0 .800 -0 .192 Item 10 0.435 0.337 -0 .660 -0.336 Item 11 0.075 0.244 0.373 -0.325 Item 12 0.431 0.853 1.104 1.129 Item 15 3.033 2.096 2.221 2.790 Constant -14.471 -13.473 -13.954 -14.857

aTo classify an individual into a diagnostic group, (1) begin with those classification coefficients under "migraine"; (2) multiply each of the 11 discriminating items of the Headache Symptom Questionnaire by its respective classification coefficient; (3) add these products, plus the value labeled "constant," to arrive at a single value; and (4) repeat steps 1 to 3, substituting for "migraine" in step 1 those classification coefficients under "combined, . . . . muscle contraction," and "cluster," respectively. (5) From the results of 1 to 4, above, you will have derived four values, one for each diagnostic group: a case is classified into that diagnostic group which has the highest of the four values.


dependent measures entered into the equation one at a time until no further increase in classificatory accuracy was obtained.

Accurate classification was obtained for 68.42% of the cases using 11 variables (items 1, 3, 4, 6-12, 15).

Table IV presents the predicted group percentages of the discriminant analysis (due to cases having missing discriminant variables, the number of cases was reduced to 114). Table V presents the classification function coefficients (Fisher's linear discriminant functions) of each discriminating variable for the four headache groups and instructions on how to classify a subject.

An additional question, tested by a McNemar test of correlated proportions (Hays, 1973), was whether the clinician's initial diagnosis or the Headache Symptom Questionnaire's classification scheme would better approximate the final diagnostic decision. The latter was based on full agreement of the two diagnosticians arrived at in a later conference. A discriminant analysis "hit" is defined as concordance with the final diagnostic decision, and a "miss" as discordance with the final diagnostic decision. A diagnostician's hit is defined as concordance with the second diagnostician's decision, and a miss as discordance with the second diagnostician's decision. There was a significant difference (p = 0.001) in the direction of diagnosticians' having a better hit rate than the discriminant analysis.

Table VI presents the table of discriminant analysis hits (agreements) and misses (disagreements) versus initial diagnostician's hits and misses. Examination of this table show that the discriminant analysis had approximately two times the number of misses as the diagnosticians initially had disagreements, and the discriminant analysis misses most often involved different patients from those with whom the diagnosticians had initial discordance (i.e., the discriminant analysis incorrectly diagnosed less than half of the cases than those on which the diagnosticians had disagreements).

Table VI. Comparison of Diseriminant Analysis Hits/Misses Based on Final Diagnosis and

Diagnosticians' Initial Hits/Misses

Diagno sis based on diseriminant analysis

Initial diagnosis based on interview

Hits Misses

Hits 70 8 Misses 30 6


DISCUSSION

The results of the factor analysis of the Headache Symptom Questionnaire lend support for their being two distinct forms of headache- migraine and muscle contraction- and one additional headache dimension concerned with duration of symptoms. The first factor is in contrast with the results of Ziegler et al. (1972), who found evidence for three distinct forms of migraine. Their analysis "revealed no single factor which contained the variables originally thought of as particularly char- acteristic of migraine-unilateral pain, nausea, visual scotoma before headache . . . " (p. 358). The loadings of factor one of the present study do contain these variables.

Previous research (Andrasik et al., i982) has shown that combined migraine-muscle contraction headache sufferers display psychological test results that are more closely related to those of migraineurs than to those of muscle contraction headache sufferers. The results of both the factor analysis, with combined headache sufferers loading more on factor 1, and the discriminant analysis of the Headache Symptom Questionnaire support this finding. The discriminant analysis had the majority of its false positives between migraine headache suffers incorrectly diagnosed as combined migraine-muscle contraction individuals and between combined migraine-muscle contraction headache sufferers incorrectly diagnosed as migraineurs.

The present results further contrast with the findings of Ziegler et al. (1972) in that cluster headaches emerged as a different entity than migraine or muscle contraction headaches: no cluster headache sufferer was predicted to be a muscle-contraction headache sufferer, and only 27.3 % were classified as migraine or combined migraine-muscle contraction; the majority of cluster patients did not load positively on any factor and, hence, loaded negatively on all three factors (it must be noted, however, that the Headache Symptom Questionnaire was not specifically designed to identify a cluster headache population).

Ziegler et al. (1972), in commenting on the surprising fact that their "tension" factor was characterized by headaches of long duration and headaches that lasted all the time, stated "it is curious that the variable 'brought on by stress' does not appear, nor the variable of 'pain in the neck during headache,' despite the frequency of the phenomena in [the] entire headache population" (p. 359). Our second factor does include these missing variables, while our third factor is similar to a factor that Ziegler termed tension. It is interesting to note that 40.6% of our migraine subjects loaded positively on this factor (factor 3).


Examination of these results may explain why Barrie e t al. (1968) found one fac to r - general distress- in their factor analysis. Their headache population consisted of migraine and combined migraine-muscle contraction headache sufferers; there were no muscle contraction subjects or cluster headache individuals. Our analysis shows that migraine and combined migraine-muscle contraction headaches are similar entities. Therefore, as their patients were essentially homogeneous diagnostically, the factor analysis broke them down on a high distress-low distress dimension.

What of the clinical/diagnostic utility of the Headache Symptom Questionnaire? Used as a brief 5-min assessment instrument, one can correctly classify 68.42 ~/0 of headache sufferers in their respective headache categories. It is of importance to note that the diagnostic agreement between trained diagnosticians is 86.4°7o. It, therefore, approaches the level of agreement reached by experienced diagnosticians but is statistically less accurate.

In conclusion, used as a brief assessment instrument, the Headache Symptom Questionnaire can accurately classify 68.42% of headache sufferers, comparable to, but statistically less accurate than, the 86.4% agreement between experienced diagnosticians. Results of a factor analysis of the Headache Symptom Questionnaire lend support for their being two commonly accepted global headache categories-vascular/migraine and muscle contraction. Combined migraine-muscle contraction headache individuals were found to be closer to migraine than to muscle contraction headache. Cluster headache-not loading positively on any fac to r -was found to be a separate entity.

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