the original 64-item dsqols was designed in germany specifically for people with type 1 diabetes ( 12 ) .
it includes 44 burden items measuring the impact of diabetes on  social relations , 
 diet restrictions ,   physical complaints ,   daily hassles ,  and  worries about the future .
 respondents are asked to rate the extent to which each of the statements meets their  point of view  on a 6-point likert scale : from  perfectly  to  not at all .  a further 10 items measure treatment satisfaction ( on a 6-point scale from  very satisfied  to  very dissatisfied  ) , and 10 more assess the personal importance of treatment goals on a 6-point likert scale from  very important  to  totally unimportant .  the design of the dsqols was based on interviews with adults with type 1 diabetes , but its precise development and item generation were not described in detail ( 12 ) .
psychometric validation of the original dsqols was undertaken using data from a sample of 657 people with type 1 diabetes attending general practice in the north rhine region of germany ( 12 ) .
a systematic review of patient - completed health outcome measures for diabetes concluded that there was good evidence for the reliability and internal and external construct validity of the german - language version of dsqols ( 18 ) .
the original german - language version was later revised after further unpublished validation work ( u. bott , unpublished observations ) .
eleven items were retained without modification , but 27 items were amended slightly to aid interpretation ( e.g. ,  diabetes restrains my future plans  amended to  diabetes interferes with my future plans  ) .
six items were omitted because of low item - scale correlations in their original analyses or weak factor loadings ( < 0.3 ) .
thus , this revised version of the dsqols includes a total of 77 items , comprising 10 individual treatment goal items , 10 treatment - satisfaction items , and 57 diabetes - specific burden items .
the validation work presented here is based upon this revised version of the german dsqols .
although the original dsqols was validated in german and not english , it was first described in an english - language journal ( 12 ) in which an english version was presented , though this was not a robust translation and was not linguistically validated . the dsqols has not , to our knowledge , been translated into any other languages .
the revised german dsqols and its unauthorized english translation were obtained from the authors . an independent translator , bilingual in german and english , who had not seen the questionnaire , carried out a second forward translation from german into u.k .
english . following international guidelines for translation and cultural adaptation of questionnaires ( 19 ) , the translator aimed for conceptual and cultural equivalence of words / phrases .
this second forward translation was compared directly with the first and discussed with a psychologist ( d.c . ) .
discrepancies with the revised german dsqols were discussed , resolved , and agreed upon between r.l.m .
the few discrepancies identified concerned the meaning of particular phrases and conceptual equivalence . to ensure content validity , clinicians and a psychologist reviewed the final english version of the questionnaire to assess its relevance , appropriateness , clarity , and comprehensiveness . cognitive debriefing ( a think - aloud technique )
they commented on the questionnaire ; its layout , comprehensiveness , redundancy , and ease of understanding and completion ; length of time taken to complete it ; and any additional comments .
feedback , at this stage of piloting , indicated that the questionnaire was comprehensible and acceptable with one exception .
response options for the 57 burden items were amended slightly so that people were asked to rate their agreement with the statements on a 6-point likert scale labeled  very strongly agree  to  do not agree at all  rather than 
 this version was discussed with a further four participants from the same center who indicated that questions and response options made sense and language was clear .
the database study collects comprehensive biomedical and psychosocial data from participants at ten centers in the u.k .
the irish study is a cluster - randomized trial evaluating two different methods of follow - up of dafne graduates ( 21 ) .
the psychosocial study is a longitudinal evaluation of structured education conducted to identify predictors of qol and glycemic outcomes .
ethics approvals were obtained from the trent research ethics committee ( rec ) , national university of ireland galway rec , and king s college rec , respectively .
inclusion criteria were similar for each study : adults ( aged 17 years ) with type 1 diabetes of at least 6-months duration who had agreed to participate in the dafne program .
eligible participants were recruited from 10 hospitals in england for the  database study ,  6 hospitals in ireland for the  irish study ,  and 12 hospitals in england and scotland for the  psychosocial study . 
the dsqols was completed by all participants in each study prior to receiving dafne training along with other psychosocial measures .
the addqol ( 10,22 ) was completed by a subsample of participants ( n = 42 ) in the irish study at baseline to assess concurrent validity .
the addqol provides a composite rating of the average weighted impact ( awi ) of diabetes , derived from ratings of 18 potentially applicable domains of life ( e.g. ,  working life ,   family life  ) , indicating the individualized impact of diabetes on the domain ( i.e. , impact 3 to 1 , weighted by importance 03 ) .
the awi score is derived by dividing the sum of the weighted ratings by the number of applicable domains .
scores for single domains and the awi range from 9 ( maximum negative impact of diabetes ) to 9 ( maximum positive impact of diabetes ) .
two overview items , scored individually , measure  present quality of life  [ scores ranging from 3 ( extremely bad ) to 3 ( excellent ) ] and  diabetes - dependent qol  [ scores ranging from 3 ( maximum negative impact of diabetes ) to 3 ( maximum positive impact of diabetes ) ] .
the who-5 ( version 5 of the world health organization well - being index ) includes five statements ( e.g. , 
i have felt cheerful and in good spirits  ) assessing positively worded depressed mood .
respondents rate their agreement with each item , using a 6-point likert scale from 0 ,  none of the time ,  to 5 ,  all of the time ,  in relation to the past 2 weeks ( 23,24 ) .
items are summed to form a total well - being score ( ranging from 0 to 25 ) , with higher scores representing greater well - being ( or less depressed mood ) .
a single - item , global measure of life satisfaction was used from the fourth edition of the personal well - being index for adults ( 25 ) .
this asks participants to rate their satisfaction with their  life right now  on a 10-point likert scale from 0 ,  completely dissatisfied ,  to 10 ,  completely satisfied . 
the latter two measures were completed only by participants in the psychosocial study and were used to assess discriminant validity .
for all three studies , demographic and clinical data were collected , including the presence of long - term complications of diabetes ( retinopathy , nephropathy , neuropathy , or macrovascular disease or sequelae thereof ) . in order to determine the structure of the 57 dsqols burden items , the database study sample ( n = 1,021 )
was split randomly in two ( using spss ) , with one - half of the sample used for exploratory factor analyses ( efas ) ( n = 510 ) and one - half used for confirmatory factor analysis ( cfa ) ( n = 511 ) .
experts differ in their recommendations for the minimum sample size required for conducting factor analyses .
comfrey and lee ( 26 ) consider a sample size of 300 as good and 500 very good , while gorsuch ( 27 ) makes recommendations based on the ratio of participants to items , stating that a minimum of five participants is required per item .
thus , with 57 items , a minimum sample of 285 is required . in a review of studies that recommended minimum sample sizes for this type of analysis , 400 was the upper limit of the recommendations ( 28 ) .
efa was carried out using maximum likelihood with geomin oblique rotation to obtain standardized estimates .
item - component loadings of > 0.30 were considered significant based on recommendations for minimum loading of an item ( 29 ) .
cfa was used to confirm the factor structure of the 57 dsqols burden items using the total sample from the database study .
 , comparative fit index ( cfi ) , a root mean square error of approximation ( rmsea ) , and standardized root mean square residual ( srmr ) were used to evaluate the fit between the model and the data .
a rmsea value < 0.08 indicates an acceptable fit to the data , while values < 0.05 indicate a good fit to the data ( 30 ) .
well - fitting models obtain srmr values < 0.05 , but values as high as 0.08 are deemed acceptable ( 31 ) .
internal consistency reliability was evaluated using cronbach  statistics and item - total correlations . as recommended by bott et al . ( 12 ) , for facilitation of comparability of the different dsqols scores , crude scores were converted to a 100% scale ( score  minimum score )  100/(maximum score  minimum score ) .
higher scores on each subscale indicate a better qol ( i.e. , less negative impact of diabetes ) or greater satisfaction with treatment .
for calculation of the preference - weighted treatment satisfaction score ( pwtss ) , ratings on each treatment goal are multiplied by the corresponding degree of satisfaction with the achievement of those goals .
the sum of those 10 products gives the pwtss , which is converted to a 100% scale .
concurrent validity was assessed by correlating ( pearson r ) dsqols subscale scores , including the pwtss , with each other and ( using a subsample of 42 from the irish study ) with scores on another , validated measure of diabetes - specific qol , the addqol ( 10 ) .
moderate to strong relationships were expected between the dsqols subscales , addqol awi score , and diabetes - dependent qol overview item .
discriminant validity was assessed by correlating ( pearson r ) the dsqols subscales , including the pwtss , and total score with measures of depressed mood ( who-5 ) , generic qol ( addqol  present qol 
overview item ) , and  life satisfaction ,  with weak to moderate correlations expected ( 32 ) . with data from the database study ,
known - groups validity was assessed by comparing the scores on the dsqols subscales , including the pwtss , between those with diagnosed diabetes - related complications and those without .
it was expected that those with complications would report significantly lower dsqols subscales scores , indicating that diabetes impaired their qol .
the original 64-item dsqols was designed in germany specifically for people with type 1 diabetes ( 12 ) .
it includes 44 burden items measuring the impact of diabetes on  social relations , 
 diet restrictions ,   physical complaints ,   daily hassles ,  and  worries about the future .
 respondents are asked to rate the extent to which each of the statements meets their  point of view  on a 6-point likert scale : from  perfectly  to  not at all .  a further 10 items measure treatment satisfaction ( on a 6-point scale from  very satisfied  to  very dissatisfied  ) , and 10 more assess the personal importance of treatment goals on a 6-point likert scale from  very important  to  totally unimportant .  the design of the dsqols was based on interviews with adults with type 1 diabetes , but its precise development and item generation were not described in detail ( 12 ) .
psychometric validation of the original dsqols was undertaken using data from a sample of 657 people with type 1 diabetes attending general practice in the north rhine region of germany ( 12 ) .
a systematic review of patient - completed health outcome measures for diabetes concluded that there was good evidence for the reliability and internal and external construct validity of the german - language version of dsqols ( 18 ) .
the original german - language version was later revised after further unpublished validation work ( u. bott , unpublished observations ) .
eleven items were retained without modification , but 27 items were amended slightly to aid interpretation ( e.g. ,  diabetes restrains my future plans  amended to  diabetes interferes with my future plans  ) .
six items were omitted because of low item - scale correlations in their original analyses or weak factor loadings ( < 0.3 ) .
thus , this revised version of the dsqols includes a total of 77 items , comprising 10 individual treatment goal items , 10 treatment - satisfaction items , and 57 diabetes - specific burden items .
the validation work presented here is based upon this revised version of the german dsqols .
although the original dsqols was validated in german and not english , it was first described in an english - language journal ( 12 ) in which an english version was presented , though this was not a robust translation and was not linguistically validated .
the dsqols has not , to our knowledge , been translated into any other languages .
the revised german dsqols and its unauthorized english translation were obtained from the authors . an independent translator , bilingual in german and english , who had not seen the questionnaire , carried out a second forward translation from german into u.k .
english . following international guidelines for translation and cultural adaptation of questionnaires ( 19 ) , the translator aimed for conceptual and cultural equivalence of words / phrases .
this second forward translation was compared directly with the first and discussed with a psychologist ( d.c . ) .
discrepancies with the revised german dsqols were discussed , resolved , and agreed upon between r.l.m . , d.c . , and the first translator .
the few discrepancies identified concerned the meaning of particular phrases and conceptual equivalence . to ensure content validity , clinicians and a psychologist reviewed the final english version of the questionnaire to assess its relevance , appropriateness , clarity , and comprehensiveness . cognitive debriefing ( a think - aloud technique )
they commented on the questionnaire ; its layout , comprehensiveness , redundancy , and ease of understanding and completion ; length of time taken to complete it ; and any additional comments .
feedback , at this stage of piloting , indicated that the questionnaire was comprehensible and acceptable with one exception .
response options for the 57 burden items were amended slightly so that people were asked to rate their agreement with the statements on a 6-point likert scale labeled  very strongly agree  to  do not agree at all  rather than 
this version was discussed with a further four participants from the same center who indicated that questions and response options made sense and language was clear .
the database study collects comprehensive biomedical and psychosocial data from participants at ten centers in the u.k .
the irish study is a cluster - randomized trial evaluating two different methods of follow - up of dafne graduates ( 21 ) .
the psychosocial study is a longitudinal evaluation of structured education conducted to identify predictors of qol and glycemic outcomes .
ethics approvals were obtained from the trent research ethics committee ( rec ) , national university of ireland galway rec , and king s college rec , respectively .
inclusion criteria were similar for each study : adults ( aged 17 years ) with type 1 diabetes of at least 6-months duration who had agreed to participate in the dafne program .
eligible participants were recruited from 10 hospitals in england for the  database study ,  6 hospitals in ireland for the  irish study ,  and 12 hospitals in england and scotland for the  psychosocial study . 
the dsqols was completed by all participants in each study prior to receiving dafne training along with other psychosocial measures .
the addqol ( 10,22 ) was completed by a subsample of participants ( n = 42 ) in the irish study at baseline to assess concurrent validity .
the addqol provides a composite rating of the average weighted impact ( awi ) of diabetes , derived from ratings of 18 potentially applicable domains of life ( e.g. ,  working life ,   family life  ) , indicating the individualized impact of diabetes on the domain ( i.e. , impact 3 to 1 , weighted by importance 03 ) .
the awi score is derived by dividing the sum of the weighted ratings by the number of applicable domains .
scores for single domains and the awi range from 9 ( maximum negative impact of diabetes ) to 9 ( maximum positive impact of diabetes ) .
two overview items , scored individually , measure  present quality of life  [ scores ranging from 3 ( extremely bad ) to 3 ( excellent ) ] and  diabetes - dependent qol  [ scores ranging from 3 ( maximum negative impact of diabetes ) to 3 ( maximum positive impact of diabetes ) ] .
the who-5 ( version 5 of the world health organization well - being index ) includes five statements ( e.g. , 
i have felt cheerful and in good spirits  ) assessing positively worded depressed mood .
respondents rate their agreement with each item , using a 6-point likert scale from 0 ,  none of the time ,  to 5 ,  all of the time ,  in relation to the past 2 weeks ( 23,24 ) .
items are summed to form a total well - being score ( ranging from 0 to 25 ) , with higher scores representing greater well - being ( or less depressed mood ) .
a single - item , global measure of life satisfaction was used from the fourth edition of the personal well - being index for adults ( 25 ) .
this asks participants to rate their satisfaction with their  life right now  on a 10-point likert scale from 0 ,  completely dissatisfied ,  to 10 ,  completely satisfied . 
the latter two measures were completed only by participants in the psychosocial study and were used to assess discriminant validity .
for all three studies , demographic and clinical data were collected , including the presence of long - term complications of diabetes ( retinopathy , nephropathy , neuropathy , or macrovascular disease or sequelae thereof ) .
in order to determine the structure of the 57 dsqols burden items , the database study sample ( n = 1,021 ) was split randomly in two ( using spss ) , with one - half of the sample used for exploratory factor analyses ( efas ) ( n = 510 ) and one - half used for confirmatory factor analysis ( cfa ) ( n = 511 ) .
experts differ in their recommendations for the minimum sample size required for conducting factor analyses .
comfrey and lee ( 26 ) consider a sample size of 300 as good and 500 very good , while gorsuch ( 27 ) makes recommendations based on the ratio of participants to items , stating that a minimum of five participants is required per item .
thus , with 57 items , a minimum sample of 285 is required . in a review of studies that recommended minimum sample sizes for this type of analysis , 400 was the upper limit of the recommendations ( 28 ) .
efa was carried out using maximum likelihood with geomin oblique rotation to obtain standardized estimates .
item - component loadings of > 0.30 were considered significant based on recommendations for minimum loading of an item ( 29 ) .
cfa was used to confirm the factor structure of the 57 dsqols burden items using the total sample from the database study .
 , comparative fit index ( cfi ) , a root mean square error of approximation ( rmsea ) , and standardized root mean square residual ( srmr ) were used to evaluate the fit between the model and the data .
a rmsea value < 0.08 indicates an acceptable fit to the data , while values < 0.05 indicate a good fit to the data ( 30 ) .
well - fitting models obtain srmr values < 0.05 , but values as high as 0.08 are deemed acceptable ( 31 ) .
internal consistency reliability was evaluated using cronbach  statistics and item - total correlations . as recommended by bott et al .
( 12 ) , for facilitation of comparability of the different dsqols scores , crude scores were converted to a 100% scale ( score  minimum score )  100/(maximum score  minimum score ) .
higher scores on each subscale indicate a better qol ( i.e. , less negative impact of diabetes ) or greater satisfaction with treatment . for calculation of the preference - weighted treatment satisfaction score ( pwtss ) , ratings on each treatment goal
the sum of those 10 products gives the pwtss , which is converted to a 100% scale .
concurrent validity was assessed by correlating ( pearson r ) dsqols subscale scores , including the pwtss , with each other and ( using a subsample of 42 from the irish study ) with scores on another , validated measure of diabetes - specific qol , the addqol ( 10 ) .
moderate to strong relationships were expected between the dsqols subscales , addqol awi score , and diabetes - dependent qol overview item .
discriminant validity was assessed by correlating ( pearson r ) the dsqols subscales , including the pwtss , and total score with measures of depressed mood ( who-5 ) , generic qol ( addqol  present qol 
overview item ) , and  life satisfaction ,  with weak to moderate correlations expected ( 32 ) . with data from the database study ,
known - groups validity was assessed by comparing the scores on the dsqols subscales , including the pwtss , between those with diagnosed diabetes - related complications and those without .
it was expected that those with complications would report significantly lower dsqols subscales scores , indicating that diabetes impaired their qol .
the demographic and clinical characteristics of each study group were very similar ( table 1 ) .
the mean age ranged from 38 to 40 years , with mean diabetes duration ranging from 16 to 18 years and mean baseline hba1c ranging from 8.3 to 8.8% .
of the 911 ( 89% ) participants for whom data were available , 396 ( 44% ) had one or more long - term complications of diabetes .
sample characteristics and dsqols scores for this analysis , data were available for 995 of 1,021 database study participants .
twenty - four had more than one - half of their data missing ; hence , the initial efa was based on n = 491 and the cfa on n = 480 .
regression imputation was used to impute values . for determination of the number of factors to extract from the efa , goodness - of - fit indices , a scree plot of eigenvalues , and
a six - factor solution was indicated and appeared to fit the data well with six interpretable factors [  = 2,999.2 , df = 1,269 , cfi = 0.898 , rmsea = 0.053 , and srmr = 0.031 ( table 2 ) ] .
this reflected the same factor structure as the revised , 57-item , unpublished german version of the dsqols and mirrored the factor analysis of the original german 44-item burden scale .
only four items had a loading of > 0.3 on a second factor ( items 2 , 12 , 13 , and 50 ) , and none had a loading > 0.4 .
factor loadings for the 57 items relating to daily restrictions and burdens [ presented in order of strength of factor loadings , with the highest factor loadings presented in boldface ( database study efa sample ) ] a cfa was run on the second half of the database study data .
model fit was good (  = 4,182.3 , df = 1,524 , p < 0.001 , cfi = 0.85 , rmsea = 0.06 , and srmr = 0.06 ) but was improved by allowing nine residuals to covary and by allowing item 41 to cross - load on the social aspects subscale (  = 3,665.6 , df = 1,514 , p < 0.001 , rmsea = 0.05 , cfi = 0.88 , and srmr = 0.05 ) .
residuals were covaried for items with very similar content and where we can assume that they share specific variance in addition to the common factor variance .
although improving overall model fit , their inclusion had very little effect on the factor loadings .
this model was then run on the full database study dataset , where model fit was slightly better (  = 5,453.2 , df = 1,514 , p < 0.001 , rmsea = 0.05 , cfi = 0.88 , and srmr = 0.05 ) , although eliminating the cross - loading did not make the fit appreciably worse (  = 5,531.5 , df = 1,515 , p < 0.001 , rmsea = 0.05 , cfi = 0.88 , and srmr = 0.05 ) .
the identification of distinct ( though highly correlated ) dsqols subscales does not preclude the existence of a single underlying diabetes - specific qol scale .
a second - order factor analysis , where each of the six factors loaded on a single second - order factor , was conducted .
fit of this model was not appreciably worse than when the factors were allowed freely to intercorrelate (  = 5,676.1 , df = 1,524 , p < 0.001 , rmsea = 0.05 , cfi = 0.88 , and srmr = 0.05 ) .
factor loadings of each subscale on the second - order factor were high ( 0.750.92 ) .
a one - factor model did not fit well (  = 13,009.1 , df = 1,539 , p < 0.001 , rmsea = 0.09 , cfi = 0.66 , and srmr = 0.07 ) .
the seven dsqols subscales each had excellent internal consistency : social aspects ( n items = 18 ,  = 0.93 ) , fear of hypoglycemia ( n items = 11 ,  = 0.94 ) , dietary restrictions ( n items = 8 ,  = 0.89 ) , physical complaints ( n items = 10 ,  = 0.89 ) , anxiety about the future ( n items = 5 ,  = 0.87 ) , daily hassles ( n items = 5 ,  = 0.85 ) , and preference - weighted treatment satisfaction scale ( n items = 20 ,  = 0.74 ) .
item total correlations for each subscale were all > 0.5 ( r = 0.510.79 ) . descriptive statistics for the dsqols subscales showed a good distribution of scores and low floor ( score of 0 ) and ceiling ( score of 100 ) effects supporting the reliability of this scale ( table 1 ) .
the six dsqols burden subscales were significantly intercorrelated ( r = 0.520.72 , p < 0.001 ) .
the dsqols subscale scores and the dsqols total score were correlated ( moderately to strongly ) with the addqol awi score and to a lesser extent ( weak to moderately ) with the diabetes - dependent addqol overview item ( table 3 ) .
correlations between dsqols subscales , addqol , and who-5 well - being and life satisfaction scales ( psychosocial study and subsample of irish study ) as predicted , all the dsqols subscales had weak to moderate , positive correlations with depressed mood ( who-5 ) , generic qol ( addqol overview item ) , and  life satisfaction ,  indicating that they are measuring different constructs ( table 3 ) .
participants with diagnosed diabetes - related complications reported significantly lower ( worse ) scores on each of the dsqols subscales and total score with the exception of the dietary restrictions and daily hassles subscales , which showed no difference ( table 4 ) .
the demographic and clinical characteristics of each study group were very similar ( table 1 ) .
the mean age ranged from 38 to 40 years , with mean diabetes duration ranging from 16 to 18 years and mean baseline hba1c ranging from 8.3 to 8.8% .
of the 911 ( 89% ) participants for whom data were available , 396 ( 44% ) had one or more long - term complications of diabetes .
twenty - four had more than one - half of their data missing ; hence , the initial efa was based on n = 491 and the cfa on n = 480 .
regression imputation was used to impute values . for determination of the number of factors to extract from the efa , goodness - of - fit indices , a scree plot of eigenvalues , and
a six - factor solution was indicated and appeared to fit the data well with six interpretable factors [  = 2,999.2 , df = 1,269 , cfi = 0.898 , rmsea = 0.053 , and srmr = 0.031 ( table 2 ) ] .
this reflected the same factor structure as the revised , 57-item , unpublished german version of the dsqols and mirrored the factor analysis of the original german 44-item burden scale .
only four items had a loading of > 0.3 on a second factor ( items 2 , 12 , 13 , and 50 ) , and none had a loading > 0.4 .
factor loadings for the 57 items relating to daily restrictions and burdens [ presented in order of strength of factor loadings , with the highest factor loadings presented in boldface ( database study efa sample ) ] a cfa was run on the second half of the database study data .
model fit was good (  = 4,182.3 , df = 1,524 , p < 0.001 , cfi = 0.85 , rmsea = 0.06 , and srmr = 0.06 ) but was improved by allowing nine residuals to covary and by allowing item 41 to cross - load on the social aspects subscale (  = 3,665.6 , df = 1,514 , p < 0.001 , rmsea = 0.05 , cfi = 0.88 , and srmr = 0.05 ) .
residuals were covaried for items with very similar content and where we can assume that they share specific variance in addition to the common factor variance .
although improving overall model fit , their inclusion had very little effect on the factor loadings .
this model was then run on the full database study dataset , where model fit was slightly better (  = 5,453.2 , df = 1,514 , p < 0.001 , rmsea = 0.05 , cfi = 0.88 , and srmr = 0.05 ) , although eliminating the cross - loading did not make the fit appreciably worse (  = 5,531.5 , df = 1,515 , p < 0.001 , rmsea = 0.05 , cfi = 0.88 , and srmr = 0.05 ) .
the identification of distinct ( though highly correlated ) dsqols subscales does not preclude the existence of a single underlying diabetes - specific qol scale .
a second - order factor analysis , where each of the six factors loaded on a single second - order factor , was conducted .
fit of this model was not appreciably worse than when the factors were allowed freely to intercorrelate (  = 5,676.1 , df = 1,524 , p < 0.001 , rmsea = 0.05 , cfi = 0.88 , and srmr = 0.05 ) .
factor loadings of each subscale on the second - order factor were high ( 0.750.92 ) .
a one - factor model did not fit well (  = 13,009.1 , df = 1,539 , p < 0.001 , rmsea = 0.09 , cfi = 0.66 , and srmr = 0.07 ) .
the seven dsqols subscales each had excellent internal consistency : social aspects ( n items = 18 ,  = 0.93 ) , fear of hypoglycemia ( n items = 11 ,  = 0.94 ) , dietary restrictions ( n items = 8 ,  = 0.89 ) , physical complaints ( n items = 10 ,  = 0.89 ) , anxiety about the future ( n items = 5 ,  = 0.87 ) , daily hassles ( n items = 5 ,  = 0.85 ) , and preference - weighted treatment satisfaction scale ( n items = 20 ,  = 0.74 ) .
item total correlations for each subscale were all > 0.5 ( r = 0.510.79 ) .
descriptive statistics for the dsqols subscales showed a good distribution of scores and low floor ( score of 0 ) and ceiling ( score of 100 ) effects supporting the reliability of this scale ( table 1 ) .
the six dsqols burden subscales were significantly intercorrelated ( r = 0.520.72 , p < 0.001 ) .
the dsqols subscale scores and the dsqols total score were correlated ( moderately to strongly ) with the addqol awi score and to a lesser extent ( weak to moderately ) with the diabetes - dependent addqol overview item ( table 3 ) .
correlations between dsqols subscales , addqol , and who-5 well - being and life satisfaction scales ( psychosocial study and subsample of irish study )
as predicted , all the dsqols subscales had weak to moderate , positive correlations with depressed mood ( who-5 ) , generic qol ( addqol overview item ) , and  life satisfaction ,  indicating that they are measuring different constructs ( table 3 ) .
participants with diagnosed diabetes - related complications reported significantly lower ( worse ) scores on each of the dsqols subscales and total score with the exception of the dietary restrictions and daily hassles subscales , which showed no difference ( table 4 ) .
english translation of the german dsqols and to examine its psychometric properties in adults with type 1 diabetes in the u.k . and
following forward - backward translation and reconciliation and piloting ( with adults with type 1 diabetes and review by clinicians in ireland ) , face and content validity of the u.k .
examination of the scale structure using efa revealed a six - factor solution , confirmed with two independent cfas , demonstrating good fit of this model to available datasets .
the structure reported here reflects the six - factor structure of the 44-burden items from the original german version .
when a single factor was fitted to the six dsqols burden subscales , this model provided a very good fit to the data , supporting the use of a dsqols total score .
moderate to strong correlations were demonstrated between dsqols scores as well as between the dsqols scores and the addqol awi score , suggesting that these are assessing similar underlying constructs providing evidence of concurrent validity .
given the mismatch between the structure of the two scales [ i.e. , the dsqols has six subscales ( summarizing its 57 items ) and the separate 20-item preference - weighted treatment satisfaction scale , and the addqol has one overall score based on the awi for all 19 domains ] , the moderate correlations are considered reasonable and the strong correlations highly satisfactory .
the weaker correlations between the dsqols subscales and the addqol diabetes - dependent overview item were to be expected , as the latter is not considered sufficient to capture the full impact of diabetes on qol ( 10 ) .
better scores on the dsqols subscales were associated with greater well - being ( less depressed mood ) , generic qol , and life satisfaction , but the correlations were sufficiently weak to indicate that various scales measure different constructs .
participants with diagnosed complications of diabetes had significantly worse scores on four of six of the dsqols burden subscales , the pwtss , and dsqols total score .
this provided support for the ability of this questionnaire tool to discriminate between different groups of respondents .
sensitivity of the dsqols to treatment effects and test - retest reliability has not been demonstrated in this study , although work using the german version has shown that it is sensitive to treatment effects in a comparison of insulin pump and multiple daily injection therapy ( 33 ) .
work is underway to examine the sensitivity of this instrument for detecting changes in qol after structured education for adults with type 1 diabetes .
there is a growing need for valid , reliable , and responsive questionnaires to assess outcomes in diabetes research and clinical practice .
management of type 1 diabetes has evolved from fixed daily insulin doses ( as prescribed ) to more flexible but complex insulin dose self - adjustment based upon carbohydrate consumption and self - monitoring of blood glucose levels .
the evidence presented indicates that dsqols is an appropriate tool for evaluating structured education courses that promote flexible intensive insulin therapy . like the addqol ,
the dsqols captures the impact of diabetes on various aspects of life known to be important for qol ( e.g. , family , friendships , and dietary freedom ) ( 10 ) .
however , the dsqols also enables participants to indicate how they feel about specific aspects of type 1 diabetes management , which are increasingly common among those who have received structured diabetes education , such as carbohydrate counting and flexible insulin dose adjustment . the dqol questionnaire ( 11 )
previously offered this type of approach to diabetes - specific qol assessment but has become outdated .
unlike existing measures , the dsqols also offers the opportunity to assess individual treatment goals as well as preference - weighted treatment satisfaction in a single instrument . the need for a focus on patient - reported outcomes in addition to biomedical end points
the length of the dsqols may be considered a limitation ; we believe this is offset by the unique contributions of its subscales , each capturing important aspects of diabetes - specific qol and reducing the need for multiple questionnaires to achieve a holistic assessment .
although its length was not criticized by participants in our studies , a shorter version of the dsqols might be more acceptable to respondents and , hence , promote its wider use in clinical and research environments .
 objectiveto develop a linguistically and psychometrically validated u.k . 
 english ( u.k./ireland ) version of the diabetes - specific quality - of - life scale ( dsqols ) for adults with type 1 diabetes.research design and methodswe conducted independent forward and backward translation of the validated german dsqols . 
 an iterative interview study with health professionals ( n = 3 ) and adults with type 1 diabetes ( n = 8) established linguistic validity . 
 the dsqols was included in three dose adjustment for normal eating ( dafne ) studies ( total n = 1,071 ) . 
 exploratory factor analysis ( efa ) was undertaken to examine questionnaire structure . 
 concurrent and discriminant validity , internal consistency , and reliability were assessed.resultsefa indicated a six - factor structure for the dsqols ( social aspects , fear of hypoglycemia , dietary restrictions , physical complaints , anxiety about the future , and daily hassles ) . 
 high internal consistency reliability was found for these factors and the weighted treatment satisfaction scale (  = 0.850.94 ) . 
 all subscales were moderately , positively correlated with the audit of diabetes - dependent quality - of - life ( addqol ) measure , demonstrating evidence of concurrent validity . 
 lower dsqols subscale scores [ indicating impaired quality of life ( qol ) ] were associated with the presence of diabetes - related complications.conclusionsthe dsqols captures the impact of detailed aspects of modern type 1 diabetes management ( e.g. , carbohydrate counting and flexible insulin dose adjustment ) that are now routine in many parts of the u.k . and ireland . the u.k . 
 english version of the dsqols offers a valuable tool for assessing the impact of treatment approaches on qol in adults with type 1 diabetes . 