this was a secondary data analysis study using hfs - ii survey data collected from four different national institutes of health  funded projects conducted at the university of virginia center for behavioral medicine research between 1998 and 2009 .
details of the methods for several of these projects have been previously published ( 9,10 ) .
all four projects included participants who had type 1 diabetes for at least 1 year and were willing to perform bg measurements at least two times every day .
study 1 had an additional inclusion criterion of having a history of two or more episodes of severe hypoglycemia during the past year .
study 4 , a survey of drivers with diabetes , had additional criteria of possessing a legal driver s license and driving at least 10,000 miles per year . in each study , participants completed a battery of questionnaires , including the hfs - ii . although studies 1 , 2 , and 3 included the entire hfs - ii scale ( i.e. , both hfs - b and hfs - w subscales ) , study 4 only used the hfs - w subscale .
participants in all studies also completed a diabetes history questionnaire , including an item to assess frequency of severe hypoglycemia over the past year .
severe hypoglycemia was defined as a hypoglycemic episode during which bg was so low that self - treatment was not possible because of mental confusion or stupor and external assistance was required .
finally , all four studies included additional psychological questionnaires , including the beck depression inventory ( 11 ) , the beck anxiety inventory ( 12 ) , the modified state - trait personality inventory ( 13 ) , and the short - form ( sf ) 12 quality - of - life inventory ( 14 ) .
these measures were used to assess the construct validity of the hfs - ii . only baseline data ( i.e. , before any intervention ) was included for the purposes of the current study .
the total number of participants with hfs - ii data was 777 , with 289 participants completing the hfs - b subscale and 488 participants completing only the hfs - w subscale . across the studies , there were no differences in sex composition , mean hba1c values , mean age , or ethnicity .
there were differences in mean duration of diabetes [ f(3,791 ) = 10.22 , p < 0.0005 ; minimum  maximum = 19.626.0 years ] and years of education [ f(2,661 ) = 10.9 , p < 0.0005 ; minimum  maximum = 14.915.9 years ] , but these did not appear to be clinically meaningful .
for the aggregate sample , mean ( sd ) age was 41.9 ( 12.6 ) years , diabetes duration was 23.8 ( 12.5 ) years , hba1c was 7.7 ( 1.4 ) % , and education was 15.6 ( 2.5 ) years .
a total of 53.3% of the subjects were female , 44.4% used insulin pumps , 63.1% reported no severe hypoglycemia in the past year , and 95.9% were white .
descriptive statistical analyses , correlations , group comparisons , and cronbach  reliability analyses were performed with pasw 18.0.2 ( spss , chicago , il ) . because factor analyses have not previously been conducted on the hfs - ii , the dimensional structure of the survey was examined with exploratory factor analysis in mplus software ( 15 ) , using polychoric correlations for handling the categorical nature of the data .
model fit was estimated using a  goodness - of - fit statistic , root mean squared error of approximation ( rmsea ) , standardized root mean squared residuals ( srmrs ) , and the tucker - lewis index ( tli ) .
currently , there is much debate in the field about cutoffs for fit indices ( 16 ) , but , in general , rmsea and srmr values < 0.10 indicate acceptable fit ( 17,18 ) and tli values > 0.90 indicate acceptable fit ( 19 ) .
hfs - b and hfs - w subscales were analyzed using the rasch partial credit model ( pcm ) in winsteps ( 20 ) .
several statistics from pcm analyses assess item quality and responses . these include 1 ) infit and outfit statistics that indicate the degree of fit between item endorsement scores and the person s level of the trait being measured , in this case foh ; 2 ) point - measure correlations , which are similar to item - total correlations , with a range of 1 to 1 on the pcm logit scale ( low and negative values being problematic ) ; and 3 ) separation values that indicate the degree of distinguishable trait levels measured by the scale , with high values desirable ( e.g. , a separation of  2  indicates that only two levels of the trait are distinguishable and a separation of  3  indicates three levels , etc ) .
separation is computed as the ratio of the test sd corrected for estimation error to root mean squared error ( rmse ) .
the total number of participants with hfs - ii data was 777 , with 289 participants completing the hfs - b subscale and 488 participants completing only the hfs - w subscale . across the studies , there were no differences in sex composition , mean hba1c values , mean age , or ethnicity .
there were differences in mean duration of diabetes [ f(3,791 ) = 10.22 , p < 0.0005 ; minimum  maximum = 19.626.0 years ] and years of education [ f(2,661 ) = 10.9 , p < 0.0005 ; minimum  maximum = 14.915.9 years ] , but these did not appear to be clinically meaningful .
for the aggregate sample , mean ( sd ) age was 41.9 ( 12.6 ) years , diabetes duration was 23.8 ( 12.5 ) years , hba1c was 7.7 ( 1.4 ) % , and education was 15.6 ( 2.5 ) years .
a total of 53.3% of the subjects were female , 44.4% used insulin pumps , 63.1% reported no severe hypoglycemia in the past year , and 95.9% were white .
descriptive statistical analyses , correlations , group comparisons , and cronbach  reliability analyses were performed with pasw 18.0.2 ( spss , chicago , il ) . because factor analyses have not previously been conducted on the hfs - ii , the dimensional structure of the survey was examined with exploratory factor analysis in mplus software ( 15 ) , using polychoric correlations for handling the categorical nature of the data .
model fit was estimated using a  goodness - of - fit statistic , root mean squared error of approximation ( rmsea ) , standardized root mean squared residuals ( srmrs ) , and the tucker - lewis index ( tli ) .
currently , there is much debate in the field about cutoffs for fit indices ( 16 ) , but , in general , rmsea and srmr values < 0.10 indicate acceptable fit ( 17,18 ) and tli values > 0.90 indicate acceptable fit ( 19 ) .
hfs - b and hfs - w subscales were analyzed using the rasch partial credit model ( pcm ) in winsteps ( 20 ) .
several statistics from pcm analyses assess item quality and responses . these include 1 ) infit and outfit statistics that indicate the degree of fit between item endorsement scores and the person s level of the trait being measured , in this case foh ; 2 ) point - measure correlations , which are similar to item - total correlations , with a range of 1 to 1 on the pcm logit scale ( low and negative values being problematic ) ; and 3 ) separation values that indicate the degree of distinguishable trait levels measured by the scale , with high values desirable ( e.g. , a separation of  2  indicates that only two levels of the trait are distinguishable and a separation of  3  indicates three levels , etc ) .
separation is computed as the ratio of the test sd corrected for estimation error to root mean squared error ( rmse ) .
table 1 summarizes the mean total hfs - ii , hfs - b , and hfs - w scores for each study and for the aggregate sample .
scores were significantly higher on the total hfs - ii and hfs - w in study 1 , in which inclusion criteria required that individuals had experienced two or more episodes of severe hypoglycemia in the previous year compared with other studies { f(2,282 ) = 8.46 , p < 0.0005 ( t12[143.4 ] = 2.43 , p = 0.016 , t13[128.3 ] = 3.83 , p < 0.0005 ) and f(3,773 ) = 26.47 , p < 0.0005 ( t12[152.1 ] = 3.84 , p < 0.0005 , t13[141.5 ] = 5.40 , p < 0.0001 , t14[174.3 ] = 7.27 , p < 0.0001 ) , respectively}. there were no differences in hfs - b ( mi = 18.0 , sd = 9.4 ; mp = 17.3 .
sd = 9.2 ) or hfs - w scores ( mi = 22.1 , sd = 14.6 ; mp = 22.1 , sd = 13.9 ) as a result of insulin regimen ( injection versus pump ) [ f(1,259 ) = 0.32 , p = 0.572 and f(1,747 ) = 0.00 , p = 0.951 , respectively ] .
hfs - b scores were significantly higher for female subjects ( m = 19.0 , sd = 9.8 ) than for male subjects ( m = 16.8 , sd = 8.5 ) [ f(1,281 ) = 4.07 , p = 0.045 ] .
hfs - w scores were also significantly higher for female subjects ( m = 23.4 , sd = 14.5 ) than for male subjects ( m = 21.0 , sd = 14.0 ) [ f(1,773 ) = 5.395 , p = 0.02 ] .
years of education were negatively correlated with hfs - b ( r = 0.28 , p = 0.0001 ) and hfs - w scores ( r = 0.10 , p = 0.016 ) .
hfs - ii score means ( sd ) by study means sharing the same subscript denote statistically significant differences ; all p < 0.0169 for total hfs - ii comparisons and
* total n for total hfs - ii and hfs - b is 279 and 289 , respectively .
cronbach  coefficients indicated a high level of internal consistency for the total hfs - ii (  = 0.94 ) , hfs - b (  = 0.85 ) , and hfs - w (  = 0.94 ) scores .
test -- retest data were available from one study ( study 3 ) that used a repeated - baseline design , with 2 months between data collection .
temporal reliability was 0.74 for the total hfs - ii , 0.81 for the hfs - b , and 0.63 for the hfs - w scales .
as table 2 shows , both the hfs - b and hfs - w correlated positively with measures of psychological distress , including the modified state - trait personality inventory anxiety , anger , and depression subscales , as well as the beck depression inventory and beck anxiety inventory .
hfs - b and hfs - w scores correlated negatively with health - related quality of life , including the sf-12 physical and mental scores . correlations and mean ( sd ) hfs - ii scores by measures of validity table 2 also shows that both hfs - b and hfs - w scores were significantly higher for those who had experienced severe hypoglycemia in the past year compared with those who had not [ f(1,281 ) = 8.956 , p = 0.003 and f(1,770 ) = 63.037 , p < 0.0005 , respectively ] , with effect sizes 0.35 for the hfs - b and 0.58 for the hfs - w .
median hfs - b item scores were 1.27 for those who experienced sh and 1.0 for those who did not experience sh , with interquartile range scores of 0.87 and 0.63 , respectively .
median hfs - w item scores were 1.44 for those with a history severe hypoglycemia and 0.94 for those with no history in the past year , with interquartile range scores of 1.13 and 0.89 , respectively .
hfs - b scores were higher for those with hba1c 7.5% compared with those with hba1c < 7.5% [ f(1,268 ) = 5.34 , p = 0.022 ] , with an effect size of 0.28 .
median hfs - b scores were 1.13 for those with hba1c 7.5% and 1.0 for those with hba1c
< 7.5% , with interquartile range scores of 0.87 and 0.73 , respectively . table 3 summarizes factor analyses results .
fit estimates for the one - factor solution were questionably acceptable [ (79 ) = 1,288.4 , p <
0.0001 ; rmsea = 0.14 , srmr = 0.13 , tli = 0.92 ] but improved in the two - factor solution [ (102 ) = 973.8 , p < 0.0001 ; rmsea = 0.10 , srmr = 0.08 , tli = 0.95 ] .
as expected , this two - factor solution reflected the two hfs - ii subscales . the  (23 )
= 314.6 between these two models indicates that the two - factor solution fit better .
a three - factor model also was tested and fit the data [ (112 ) = 630.1 , p < 0.0001 ; rmsea = 0.08 , srmr = 0.06 , tli = 0.98 ] , with only four hfs - b items loading onto a third factor .
based on study hypotheses and the fit of the two - factor solution reflecting the hfs - ii subscales , irt analysis was performed on the two - factor solution .
exploratory factor analysis results * pcm ranking of the measures is on a scale from 1 ( the most frequently strongly endorsed item on each scale ) to the highest number on each scale representing the least frequently strongly endorsed item .
some rankings indicate tied measures . in the two - factor solution , 13 of 15 hfs - b items loaded onto the first factor , with coefficients ranging from 0.33 to 0.87 ( see table 3 ) .
the only items that did not load within this two - factor solution range were hfs - b3 and hfs - b4 .
all 18 hfs - w items loaded onto the second factor , with coefficients ranging from 0.43 to 1.04 .
the correlation between these two subscales was r = 0.60 ( p < 0.0005 ) .
optimal assessment is indicated by matching between person trait - level scores and item endorsement scores .
nearly all item endorsement scores matched with individual person trait scores within the range of the highest to lowest scores for both people and items .
for hfs - b item endorsement scores , m = 0.00 ( by definition ) and sd = 0.58 and for person hfs - b trait - level scores , m = 0.86 , sd = 0.83 .
for hfs - w item endorsement scores , m = 0.00 ( by definition ) and sd = 0.44 and for person hfs - w trait - level scores , m = 1.01 and sd = 1.26 .
for both scales , the mean person trait - level score was slightly lower than mean item endorsement score , and person trait - level variability was greater than item variability for the respective scales , which was acceptable . items were rank - ordered separately for each subscale from the most frequently strongly endorsed item to the least frequently strongly endorsed item , on average ( see table 3 ) .
twelve hfs - b items showed excellent fit ( item responses were as expected ) , with proper ranges of infit values ( 0.641.28 ) and outfit values ( 0.671.09 ) .
point - measure correlations for these items ranged from 0.40 to 0.72 , which is excellent .
for hfs - b3 and hfs - b4 , infit and outfit values indicated less fit than expected , had low point - measure correlations , and were the two most frequently strongly endorsed items , on average .
for hfs - b8 , outfit was better than expected , and it was the least frequently strongly endorsed item with lower variability compared with other hfs - b items .
separation for the hfs - b was 7.92 , indicating nearly eight statistically distinguishable trait levels and excellent discrimination quality .
seventeen hfs - w items showed excellent fit , with ranges of infit values ( 0.771.25 ) and outfit values ( 0.721.27 ) .
no other statistics ( item endorsement score , point - measure correlation ) were extreme , so concern for this item was negligible .
separation for the hfs - w was 9.35 , indicating over nine statistically distinguishable trait levels and excellent discrimination quality .
table 1 summarizes the mean total hfs - ii , hfs - b , and hfs - w scores for each study and for the aggregate sample .
scores were significantly higher on the total hfs - ii and hfs - w in study 1 , in which inclusion criteria required that individuals had experienced two or more episodes of severe hypoglycemia in the previous year compared with other studies { f(2,282 ) = 8.46 , p < 0.0005 ( t12[143.4 ] = 2.43 , p = 0.016 , t13[128.3 ] = 3.83 , p < 0.0005 ) and f(3,773 ) = 26.47 , p < 0.0005 ( t12[152.1 ] = 3.84 , p < 0.0005 , t13[141.5 ] = 5.40 , p < 0.0001 , t14[174.3 ] = 7.27 , p < 0.0001 ) , respectively}. there were no differences in hfs - b ( mi = 18.0 , sd = 9.4 ; mp = 17.3 .
sd = 9.2 ) or hfs - w scores ( mi = 22.1 , sd = 14.6 ; mp = 22.1 , sd = 13.9 ) as a result of insulin regimen ( injection versus pump ) [ f(1,259 ) = 0.32 , p = 0.572 and f(1,747 ) = 0.00 , p = 0.951 , respectively ] .
hfs - b scores were significantly higher for female subjects ( m = 19.0 , sd = 9.8 ) than for male subjects ( m = 16.8 , sd = 8.5 ) [ f(1,281 ) = 4.07 , p = 0.045 ] .
hfs - w scores were also significantly higher for female subjects ( m = 23.4 , sd = 14.5 ) than for male subjects ( m = 21.0 , sd = 14.0 ) [ f(1,773 ) = 5.395 , p = 0.02 ] .
years of education were negatively correlated with hfs - b ( r = 0.28 , p = 0.0001 ) and hfs - w scores ( r = 0.10 , p = 0.016 ) .
hfs - ii score means ( sd ) by study means sharing the same subscript denote statistically significant differences ; all p < 0.0169 for total hfs - ii comparisons and
* total n for total hfs - ii and hfs - b is 279 and 289 , respectively .
cronbach  coefficients indicated a high level of internal consistency for the total hfs - ii (  = 0.94 ) , hfs - b (  = 0.85 ) , and hfs - w (  = 0.94 ) scores . test -- retest data were available from one study ( study 3 ) that used a repeated - baseline design , with 2 months between data collection .
temporal reliability was 0.74 for the total hfs - ii , 0.81 for the hfs - b , and 0.63 for the hfs - w scales .
as table 2 shows , both the hfs - b and hfs - w correlated positively with measures of psychological distress , including the modified state - trait personality inventory anxiety , anger , and depression subscales , as well as the beck depression inventory and beck anxiety inventory .
hfs - b and hfs - w scores correlated negatively with health - related quality of life , including the sf-12 physical and mental scores . correlations and mean ( sd ) hfs - ii scores by measures of validity table 2 also shows that both hfs - b and hfs - w scores were significantly higher for those who had experienced severe hypoglycemia in the past year compared with those who had not [ f(1,281 ) = 8.956 , p = 0.003 and f(1,770 ) = 63.037 , p < 0.0005 , respectively ] , with effect sizes 0.35 for the hfs - b and 0.58 for the hfs - w .
median hfs - b item scores were 1.27 for those who experienced sh and 1.0 for those who did not experience sh , with interquartile range scores of 0.87 and 0.63 , respectively .
median hfs - w item scores were 1.44 for those with a history severe hypoglycemia and 0.94 for those with no history in the past year , with interquartile range scores of 1.13 and 0.89 , respectively .
hfs - b scores were higher for those with hba1c 7.5% compared with those with hba1c <
7.5% [ f(1,268 ) = 5.34 , p = 0.022 ] , with an effect size of 0.28 . hfs - w scores did not differ , with an effect size of 0.12 .
median hfs - b scores were 1.13 for those with hba1c 7.5% and 1.0 for those with hba1c
fit estimates for the one - factor solution were questionably acceptable [ (79 ) = 1,288.4 , p < 0.0001 ; rmsea = 0.14 , srmr = 0.13 , tli = 0.92 ] but improved in the two - factor solution [ (102 ) = 973.8 , p < 0.0001 ; rmsea = 0.10 , srmr = 0.08 , tli = 0.95 ] .
as expected , this two - factor solution reflected the two hfs - ii subscales . the  (23 )
= 314.6 between these two models indicates that the two - factor solution fit better .
a three - factor model also was tested and fit the data [ (112 ) = 630.1 , p < 0.0001 ; rmsea = 0.08 , srmr = 0.06 , tli = 0.98 ] , with only four hfs - b items loading onto a third factor .
based on study hypotheses and the fit of the two - factor solution reflecting the hfs - ii subscales , irt analysis was performed on the two - factor solution .
exploratory factor analysis results * pcm ranking of the measures is on a scale from 1 ( the most frequently strongly endorsed item on each scale ) to the highest number on each scale representing the least frequently strongly endorsed item .
some rankings indicate tied measures . in the two - factor solution , 13 of 15 hfs - b items loaded onto the first factor , with coefficients ranging from 0.33 to 0.87 ( see table 3 ) .
the only items that did not load within this two - factor solution range were hfs - b3 and hfs - b4 .
all 18 hfs - w items loaded onto the second factor , with coefficients ranging from 0.43 to 1.04 .
the correlation between these two subscales was r = 0.60 ( p < 0.0005 ) .
optimal assessment is indicated by matching between person trait - level scores and item endorsement scores .
nearly all item endorsement scores matched with individual person trait scores within the range of the highest to lowest scores for both people and items .
for hfs - b item endorsement scores , m = 0.00 ( by definition ) and sd = 0.58 and for person hfs - b trait - level scores , m = 0.86 , sd = 0.83 .
for hfs - w item endorsement scores , m = 0.00 ( by definition ) and sd = 0.44 and for person hfs - w trait - level scores , m = 1.01 and sd = 1.26 .
for both scales , the mean person trait - level score was slightly lower than mean item endorsement score , and person trait - level variability was greater than item variability for the respective scales , which was acceptable . items were rank - ordered separately for each subscale from the most frequently strongly endorsed item to the least frequently strongly endorsed item , on average ( see table 3 ) .
twelve hfs - b items showed excellent fit ( item responses were as expected ) , with proper ranges of infit values ( 0.641.28 ) and outfit values ( 0.671.09 ) .
point - measure correlations for these items ranged from 0.40 to 0.72 , which is excellent . for hfs - b3 and hfs - b4 , infit and outfit values indicated less fit than expected , had low point - measure correlations , and were the two most frequently strongly endorsed items , on average .
for hfs - b8 , outfit was better than expected , and it was the least frequently strongly endorsed item with lower variability compared with other hfs - b items .
separation for the hfs - b was 7.92 , indicating nearly eight statistically distinguishable trait levels and excellent discrimination quality .
seventeen hfs - w items showed excellent fit , with ranges of infit values ( 0.771.25 ) and outfit values ( 0.721.27 ) .
no other statistics ( item endorsement score , point - measure correlation ) were extreme , so concern for this item was negligible .
separation for the hfs - w was 9.35 , indicating over nine statistically distinguishable trait levels and excellent discrimination quality .
the survey demonstrated strong internal consistency , with reliability coefficients 0.85 for the total hfs - ii and subscales .
temporal reliability was adequate , ranging from 0.81 ( hfs - b ) to 0.63 ( hfs - w ) , although it is important to note that foh would not be expected to stay completely stable over time .
previous studies have shown that levels of foh can increase after traumatic experiences with severe hypoglycemia ( 21 ) and decrease after interventions that reduce the frequency of hypoglycemia ( 22,23 ) .
several findings support the validity of the hfs - ii , including significantly higher scores for both subscales in patient populations expected to have higher levels of foh , such as those who experience more frequent severe hypoglycemia .
in addition , hfs - b scores , but not hfs - w scores , were higher in patients with poorer glycemic control , indicative of more hyperglycemia .
female subjects also had significantly higher hfs - ii scores , replicating numerous studies that found higher levels of emotional and physical symptoms in female subjects across a broad range of self - report instruments .
construct validity was additionally supported by the positive correlations between the hfs - ii and other valid measures of psychological distress , including anxiety and depression . as expected , higher hfs - ii scores were negatively related to quality of life , with the hfs - w subscale more strongly related to mental and emotional quality of life and the hfs - b subscale more strongly related to physical quality of life .
factor analyses supported a two - factor solution over a one - factor solution , with item loadings justifying the structure and separate scoring of the hfs - b and hfs - w subscales . a recent swedish study ( 24 ) found a three - factor solution for the hfs - i in type 1diabetic patients , with the third factor comprising hfs - w items describing worries about being alone during hypoglycemia .
the current study tested a three - factor solution for the hfs - ii but did not replicate the swedish findings .
the three - factor solution for the hfs - ii did provide slightly better fit , but the third factor comprised a few items on the hfs - b , not the hfs - w , subscale .
it is almost always the case that increasing the number of factors results in better fit , although this does not necessarily result in better understanding of a scale .
unfortunately , the hfs - b subscale was not included in some of the datasets analyzed for this study . additional analysis of datasets with more hfs - b data are needed to determine whether this factor will be confirmed and whether it improves the utility of the hfs - ii .
rasch pcm analyses indicated very good results for the items in the two hfs - ii subscales .
both subscales had excellent separation , reasonable item - to - person matching , and good item - fit statistics , indicating that they are appropriate measures of the constructs represented in the two - factor solution .
two items on the hfs - b ( reduce insulin when bg is low and measure bg six or more times per day ) yielded very low factor loadings , and the rasch pcm analysis indicated that these items were , on average , the most frequently strongly endorsed . although sometimes this type of result may indicate appropriate removal of these items from the instrument , this is not recommended for two reasons .
irt analysis indicated that these items tended to be strongly endorsed by most individuals ; therefore , the failure to strongly endorse these items may be important information to have about a person s behavioral reactions to low bg levels .
second , maintaining these items , and keeping the hfs - ii consistent across studies and translations , allows researchers to compare results more easily across various populations , translations , and research .
the mean scores and comparisons across different patient populations generated by this study may help to guide clinical interpretations of hfs - ii scores .
for example , higher hfs - ii scores , on both subscales but especially on the hfs - w subscale , are expected in patients with a recent history of severe hypoglycemia . on the other hand
, patients in poorer glycemic control did not exhibit higher hfs - w subscale scores but did exhibit higher hfs - b scores .
in addition , whereas hfs - w scores were more strongly related to lower quality of life in terms of emotional distress , hfs - b scores were more strongly related to lower quality of life in terms of physical burden and impairment .
the original purpose of the two subscale construction of the hfs was to assess both the behavioral and the affective dimensions of patient experience and reaction to hypoglycemia .
these results also support the need to administer the entire hfs - ii scale in order to assess these different dimensions of foh and not just the hfs - w subscale , which has been done in some studies .
it still is premature , however , to generalize these findings to translated versions of the hfs - ii , and it is a limitation of this study that only u.s .
additional research is needed to validate other versions of the scale and to compare foh across different cultures and countries
. other limitations of this study include the substantially lower number of hfs - b surveys for analysis and the exclusion of individuals with type 2 diabetes , which was beyond the scope of this article .
future studies are needed of the psychometric properties of the hfs - ii in type 2 diabetes , as well as in pediatric patients and their parents .
english version of the hfs - ii is a psychometrically valid and reliable instrument for adults with type 1 diabetes , with potential clinical as well as scientific utility for the assessment of foh .
 objectiveto perform the first comprehensive psychometric evaluation of the hypoglycemia fear survey - ii ( hfs - ii ) , a measure of the behavioral and affective dimensions of fear of hypoglycemia , using modern test - theory methods , including item - response theory ( irt).research design and methodssurveys completed in four previous studies by 777 adults with type 1 diabetes were aggregated for analysis , with 289 subjects completing both subscales of the hfs - ii and 488 subjects completing only the worry subscale . the aggregated sample ( 53.3% female , 
 44.4% using insulin pumps ) had a mean age of 41.9 years , diabetes duration of 23.8 years , hba1c value of 7.7% , and 1.4 severe hypoglycemic episodes in the past year . 
 data analysis included exploratory factor analysis using polychoric correlations and irt . 
 factors were analyzed for fit , trait - level locations , point - measure correlations , and separation values.resultsinternal and test - retest reliability was good , as well as convergent validity , as demonstrated by significant correlations with other measures of psychological distress . 
 scores were significantly higher in subjects who had experienced severe hypoglycemia in the past year . 
 factor analyses validated the two subscales of the hfs - ii . 
 item analyses showed that 12 of 15 items on the behavior subscale , and all of the items on the worry subscale had good - fit statistics.conclusionsthe hfs - ii is a reliable and valid measure of the fear of hypoglycemia in adults with type 1 diabetes , and factor analyses and irt support the two separate subscales of the survey . 