Functional Family Therapy (FFT) for Young People in Treatment for Non-opioid Drug Use: A Systematic Review

1.1 DESCRIPTION OF THE CONDITION

Youth drug abuse ¹ of the kind that persists beyond the experimentation phase is a severe problem worldwide (United Nations Office on Drugs and Crime (UNODC), 2010). Abuse of non-opioid drugs such as cannabis, amphetamine and cocaine is strongly associated with a broad range of negative health implications such as traffic accidents, sexually transmitted diseases, mental problems and suicide as well as social problems including poor academic achievement, delinquency and violent behavior (Deas & Thomas, 2001; Essau, 2006; Rowe & Liddle, 2006; Office of National Drug Control Policy (ONDCP), 2000; Shelton, Taylor, Bonner, & van den Bree, 2009; Nordstrom & Levin, 2007; Lynskey & Hall, 2000).

While cannabis, amphetamine, cocaine and other non-opioid drugs remain illegal in most countries, surveys indicate widespread prevalence. In the US, 25.5 percent of 12^th-grade students report having used an illicit drug (any kind) within the last month (Johnston, O'Malley, Miech, Bachman, & Schulenberg, 2014). In Canada, 21 percent of 15-24 year olds report having used of some kind of illicit drugs within the last year (Health Canada, 2011). In Australia, seven percent 12-17 year olds report using some kind of drug within the last month (White & Smith, 2009). The European Monitoring Centre for Drugs and Drug Addiction has found that that within Europe prevalence differs significantly from country to country but that overall around a quarter of Europeans report having used some kind of illicit drug in their lifetime (European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), 2013).

The prevalence of specific kinds of illicit drug abuse varies significantly, with cannabis generally being the most commonly used drug. In the US, 22.7 percent of 12^th-grade students report having used marijuana/hashish (types of cannabis), 4.1 percent amphetamine, and 1.1 percent cocaine during the last 30 days before the National Survey on Drug Use conducted in 2013 (Johnston et al., 2014). The European Drug Report of 2013 indicates that 11.7 percent of the 15 to 34 year-olds in Europe have used cannabis, 1.3 percent amphetamine, and 1.9 percent used cocaine during the last year (EMCDDA, 2013).

Although not all young drug users progress to severe dependence, some do and may therefore require treatment (see e.g. Crowley, Macdonald, Whitmore & Mikulich, 1998). Research draws attention to the significant gap between the number of young people classified as in need of treatment and the number of young people who actually receive such treatment (Substance Abuse and Mental Health Services Administration (SAMHSA), 2010; National Survey on Drug Use and Health (NSDUH), 2007). In the US, for example, 7.2 million people aged 12 or older are classified as needing treatment for illicit drug abuse, but only 1.4 million of these young people actually receive treatment at a specialty facility for an illicit drug abuse problem (SAMHSA, 2011).

The treatment usually provided to young people is delivered in outpatient settings. Accordingly, 90 percent of the 89,521 clients under age 18 registered in substance abuse treatment in 2012 by SAMHSA were in outpatient treatment, which is the same proportion as the total treatment population (Substance Abuse and Mental Health Services Administration (SAMHSA), 2013). Equal proportions of the clients under age 18 were enrolled in facilities with a primary focus on substance abuse treatment and in facilities whose primary focus were provision of a mix of mental health and substance abuse treatment services; this differs from the total treatment population as youth tend to be treated in dual focus facilities more often than adults (SAMHSA, 2013). Cognitive-behavioral therapy and motivational interviewing are specific therapeutic approaches that are used at least sometimes by most treatment facilities (91% and 87% respectively: SAMHSA, 2013).

There is growing public concern about the effectiveness and high cost of available treatments for young people, and the high rates of treatment dropout and post-treatment relapse to drug abuse (Austin, Macgowan, & Wagner, 2005; Najavits & Weiss, 1994; Stanton & Shadish, 1997). While relapse must be acknowledged as an expected part of any treatment process targeting individual drug use, efforts should be made to make treatment as attractive, accessible and relevant as possible for young people in order to minimize the risk of unwarranted dropout and continuous relapse (Simmons et al., 2008; National Institute on Drug Abuse (NIDA), 2009). Furthermore, the services provided should be empirically supported to increase the likelihood that (a) treatment will be successful, and (b) public spending supports the interventions that are the most effective.

Researchers point to the fact that many research projects have empirically validated different types of treatment approaches as effective for young drug users (e.g. Rowe & Liddle, 2006; Waldron, Turner, & Ozechowski, 2006; Williams, Chang, & Addiction Centre Adolescent Research Group, 2000; Austin et al., 2005). The effectiveness, however, depends upon the interplay between a specific intervention and individual factors such as gender, ethnicity, family composition, co-morbidity and history of drug abuse (Brannigan, Schackman, Falco, & Millman, 2004; Hawkins 2009; Horsfall, Cleary, Hunt, & Walter 2009). For example, research suggests that treatment outcomes of a specific program such as Functional Family Therapy may vary for different ethnic groups (Hops et al, 2011; Flicker, Waldron, Turner, Brody, & Hops, 2011). The current challenge in the field of substance abuse treatment for young people is therefore to establish not only what works best but also what works for different subgroups.

In terms of treatment types, there is some documentation of promising individually-based cognitive and motivational therapies (Waldron & Turner, 2008; Kaminer, 2008; Deas & Thomas, 2001; Galanter & Kleber, 2008). Family-based approaches on the other hand may be equally effective. Family therapy encompasses a range of different interventions with varying theoretical sources, including behavioral and cognitive behavioral theory, structural and strategic family theory, and family systems theory (Williams et al., 2000; Austin et al., 2005). Some reviews have suggested that these family-based therapies are superior to individual-based programs in reducing youth drug abuse (Williams et al., 2000; Lipsey, Tanner-Smith, & Wilson, 2010; Waldron, 1997).

Young people with persistent drug abuse have unique needs due to their particular cognitive and psychosocial development. Young people are especially sensitive to social influence, with family and peer groups being highly influential. Youth drug treatments which facilitate positive parental and peer involvement, and which integrate other systems in which the young person participates (such as schools, social services, and justice authorities) are thus key to reducing drug abuse by young people (NIDA, 2009). A number of studies and reviews have showed positive results for family therapies in general, but there is a need to synthesize individual study results for specific family therapies to determine whether and to what extent specific family therapy interventions work for young drug abusers (Williams et al., 2000; Austin et al., 2005; Waldron & Turner, 2008; Kaminer, 2008; Deas & Thomas, 2001).

This review is concerned specifically with Functional Family Therapy (hereafter FFT) (Alexander & Parsons, 1973; Alexander & Parsons, 1982; Rowe & Liddle, 2003), as aggregated evidence for the effects of this approach is lacking. The review will seek to clarify the effects of the FFT program for relevant groups of young people aged 11-21, and will focus on young people enrolled in treatment for drug abuse, irrespective of how their problem is defined. Enrolment in treatment is taken to imply that the severity of the young person's drug abuse has compelled a close, significant adult (for example, teacher, parent, social services, or school counselor) to demand that the young person enters treatment. FFT is an intervention offered as an outpatient treatment ² to young people age 11-21 that are living with their families ³ .

This review focuses solely on non-opioid drug abuse ⁴ , and is one in a series of reviews on manual-based family therapy interventions for young people in treatment for non-opioid drug abuse ⁵ .

1.2 DESCRIPTION OF THE INTERVENTION

Functional Family Therapy (FFT) is a short-term, manual-based, behaviorally oriented family therapy program for young people with behavior problems such as drug abuse, juvenile delinquency and violence. Delivered in an outpatient setting, it aims to help young people and their families by improving family interactions and relationship function by addressing dysfunctional individual behavior (Sexton & Alexander, 2000; Sexton & Turner, 2011).

In an FFT program, the therapist provides intensive family therapy in an attempt to change the patterns of family interaction that are contributing to the problem behavior and to help family members develop specific skills in, for example, communication, conflict resolution, problem solving, and effective parenting. After the desired behavioral change has been achieved within the family, the therapist helps the family generalize changes to other situations and settings, such as school, community, and peers, and identifies support that can help to maintain the progress made (Sexton & Alexander, 2003; Onedera, 2006).

As with many other forms of family therapy, FFT targets young people and their families as a system. As such, it recognizes the important role of the family system in the development and treatment of young people's drug abuse problems (Ozechowski & Liddle, 2000); indeed, the FFT model asks that there be no ‘identified patient’. While a specific FFT intervention may focus on improving specific problems such as drug abuse, the FFT approach in itself adds a broader view of the change process and clinical outcomes by switching from an individual problem focus to a relational perspective. The intervention is designed to help families recalibrate their interaction patterns and improve family relations, and through this achieve individual goals such as decreased drug abuse (Alexander, Waldron, Robbins, & Neeb, 2013).

FFT was developed in the late 1960s and early 1970s (Alexander & Parsons, 1973) with the model described in full by Alexander and Parsons in the early 1980s (Alexander & Parsons, 1982). It was developed to serve diverse populations of under-served and at-risk adolescents and their families because these populations lacked resources, were difficult to treat, and were often perceived by professionals as lacking the motivation for change. The founders of FFT realized that successful treatment of these populations required service providers who were sensitive to the needs of these diverse families, who were competent to work with them, and who understood why the families had traditionally resisted treatment (Sexton & Alexander, 2003). The development of the FFT program has continued, and the therapy has been refined in response to the results of research and the experiences from successful implementation (Alexander & Robbins, 2010).

In a systematic review conducted by Austin et al. (2005), FFT appeared as one of five interventions identified as consistent with the majority of guidelines for effective treatment for adolescents with substance abuse. Austin et al. (2005) also note, however, that there is some inconsistency in the research on outcomes of FFT and that long-term follow-up assessment is needed. In a meta-analytical study, Waldron & Turner (2008) synthesized findings from 17 studies evaluating outpatient treatments for substance-abusing youth, including several therapy models, among them FFT, other family therapy approaches, group CBT, individual CBT and minimal treatment conditions. Waldron & Turner (2008) found that the effect size associated with reductions in drug abuse was significantly larger for family therapy relative to the minimal treatment condition, but the meta-analysis did not establish one of the treatment approaches as clearly superior to any other in terms of treatment effectiveness for substance-abusing youth.

1.3 HOW THE INTERVENTION MIGHT WORK

FFT was originally designed to aid in the family unit becoming healthier; a reduction in recidivism rates for juveniles and the treatment of substance use has subsequently grown out of the model, but was not a driving force in its design. Where FFT is applied specifically to youth with non-opioid drug use problems, however, two rather different primary objectives can be discerned: 1) to eliminate or reduce young people's drug abuse, and 2) to change behaviors associated with drug abuse in young people and their families. Randomized controlled trials and systematic reviews have indicated that FFT can reduce drug abuse in participants, can contribute to a reduction in behavioral problems and delinquency, and is associated with improvements in family communication patterns and relationships (Austin et al., 2005; Waldron, Slesnick, Brody, Turner, & Peterson, 2001; Waldron & Turner, 2008; Hogue & Liddle, 2009; Stanton & Shadish, 1997).

Psychodynamic, behavioral, and social learning have been the key theories that shaped have FFT (Alexander et al., 2013). Fundamentally, this theoretical bedrock indicates that problem behavior is not approached as a mere reflection of individual psychopathology. Rather both positive and negative behavior is viewed in the social context, meaning that therapists focus their attention more on interactional dynamics. Furthermore, FFT is influenced by family systems and communication theories infusing the holistic perspective and implying that therapists view social roles and relationships as central, if not causative, aspects of problem behavior (Alexander et al., 2013). Building on these theories, FFT requires that the therapists focus on the relational functions of all family members' behaviors relevant to the problem behavior (e.g. drug abuse) of the referred youth. In other words, FFT theorizes that changing individual drug abuse may be achieved through improving family relations and reducing dysfunctional interaction.

A basic premise of FFT is therefore that family members of the referred substance-abusing youth participate in the treatment process. The decision about who is to participate in FFT sessions in a particular case is based on the therapist's understanding of which family members will be important for the change process involving the referred youth (Alexander et al., 2013). While parents (or parental figures) are expected to participate, they are not necessarily expected to be motivated at the treatment outset to keep the family integrated. Parents, especially stepparents, may enter FFT motivated to have the youth removed from the home, and FFT treatment encompasses specify strategies to engage them in a positive change process (Alexander et al., 2013).

The program outcomes may be affected by mediating factors such as participant characteristics and program mechanisms. Participant characteristics that have been found to predict program drug abuse reduction or abstinence were: history and severity of drug abuse pretreatment; level of general peer and parental support, particularly in relation to non-drug use; and higher levels of school attendance and functioning pretreatment (Williams et al., 2000). More information is required by practitioners on the impact of other characteristics such as age, gender, ethnicity, family composition (e.g., single parenting), and co-occurring conditions. These participant characteristics are potential predictors of treatment outcome and practitioners need to be able to assess the program's relevance for any particular type of client.

Treatment variables with positive impacts on treatment outcomes have been identified in a number of reviews of a range of treatments for youth drug abuse (Waldron & Turner, 2008; Williams et al., 2000). Treatment completion is the variable most consistently related to reduction in drug abuse (Williams et al., 2000; Waldron & Turner, 2008). While it is established that building a therapeutic alliance early in treatment increases the likelihood that young people complete treatment and reduce their drug abuse (Waldron & Turner, 2008), it remains unclear whether this is a direct effect or an indicator of treatment motivation (which itself has been shown to have a positive impact on treatment outcome). Either way, these findings point to the importance of the FFT components of ‘engagement’ and ‘motivation’ as influences on treatment compliance and attendance.

1.4 WHY IS IT IMPORTANT TO DO THIS REVIEW

Persistent drug abuse among young people is a significant social problem, and the treatment of young people's drug abuse is challenging and costly, not least because the treatments for such problems are plagued by high dropout rates and posttreatment relapse. Research suggests that nearly half of the young drug users who enter treatment never complete it (SAMHSA), 2008). There is a need to identify effective treatments that address young people's drug abuse problems and that minimize dropout and post-treatment relapse. Furthermore, the growing interest among policymakers in increasing funding for evidence-based interventions was a strong motivation for collecting further evidence with a systematic review on a promising treatment for young drug users.

By aggregating the results from all available individual studies on FFT, this review will contribute to the body of knowledge on the treatment of young drug-users and their families. The review will inform practice by exploring the effects of FFT for relevant client groups.

3.1 TITLE REGISTRATION AND REVIEW PROTOCOL

The title for this systematic review was approved in The Campbell Collaboration on 31 May, 2010. The review protocol was approved on 21 September 2014. Title and protocol are available at: http://campbellcollaboration.org/lib/project/173/.

3.2 CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW

3.3 SEARCH METHODS FOR IDENTIFICATION OF STUDIES

The search was performed by one of the review authors (AKJ)

3.4 DATA COLLECTION AND ANALYSIS

4.1 RESULTS OF THE SEARCH

We ran the main searches in June 2013. We searched 14 international and Nordic bibliographic databases, performed an extensive search for grey literature, and hand searched five core journals in October 2013 (see section 3.3).

After excluding duplicates, we found 6719 potential relevant records from the database search (bibliographic databases, 4343; grey literature, 725; hand searches and others, 1,651

All 6719 records were screened based on title and abstract, and 108 records were retrieved and screened in full text. Of these, 93 did not fulfill the screening criteria and were excluded.

Three papers met the inclusion criteria and were data-extracted by the review's authors.

A total of two unique studies, reported in three papers, were included in the review. Further details of the included and excluded studies are given in section 9.

4.2 DESCRIPTION OF THE STUDIES

4.2.2 Excluded studies

Six studies which initially appeared to be eligible were excluded. The primary reason for exclusion of four of these studies is that participants were not in outpatient drug treatment primarily for non-opioid drug use. The remaining two studies focused on the comparison between ethnic matching of therapist and client respectively on the therapeutic alliance. The full characteristics of excluded studies are given in section 9.2.

4.2.3 Studies awaiting assessment

A search of the clinicaltrials.gov database revealed two potentially relevant studies that are ongoing. These are listed in Table 9.5.

4.3.1 Sequence generation

Both included studies were described as randomized by the trial investigators. Waldron et al. (2001) reported the procedure for randomization and was judged as having a low risk of bias for sequence generation. Friedman (1989) did not report the randomization procedure and was therefore judged as having an unclear risk of bias on this domain.

4.3.2 Allocation concealment

Neither of the two studies reported how allocation was handled, and both were therefore judged as having an unclear risk on this domain.

4.3.3 Confounders

This item is only relevant for non-randomized studies and consequently was not assessed.

4.3.4 Blinding

This item was judged on a 5 point scale/unclear in accordance with the risk of bias tool described in section 3.4.3. As is common in social interventions, and especially when outcomes are self-reported, there is an inherent risk of bias given the impossibility of blinding the participants or those delivering the interventions. Both studies were rated as unclear for blinding of outcome assessors because of lack of reporting on data collection and blinding procedures.

4.3.5 Incomplete outcome data

This item was judged on a 5 point scale/unclear in accordance with the risk of bias tool described in section 3.4.3. Dropout rates were reported in both studies, but only Waldron et al., (2001) performed analysis for any imbalance in attrition between groups. Waldron et al. (2001) was rated 1 for incomplete outcome data with respect to the outcomes “abstinence or reduction of drug use” and ‘unclear’ with respect to the outcome “risk behavior”. Friedman (1989) only reported on ‘education or vocational involvement ‘ and was rated 3 for incomplete outcome data.

4.3.6 Selective reporting

The study by Friedman (1989) was rated 4 due to no reporting of outcome results except for ‘Education or vocational involvement’. The trial investigator stated that there was no difference between the two groups with respect to number of sessions attended, but no numbers were provided. Waldron et al. (2001) was rated 1 with respect to the outcomes “abstinence or reduction of drug use” and “risk behavior” because these outcomes were reported carefully. However, the outcome “family functioning” in this study was rated 3 because the numeric data was missing.

4.3.7 Other potential sources of bias

His item was judged on a 5 point scale/unclear in accordance with the risk of bias tool described in section 3.4.3. In this part of the risk of bias tool we paid special attention to how the trial investigators measured treatment adherence. The study by Friedman (1989) was rated 3 because only the therapist adherence for the FFT condition was measured. Waldron et al. (2001) was rated 1 because they addressed treatment adherence and report that a high adherence was achieved.

4.3.8 A priori protocol

Explicitly stating a priori hypotheses and methods without prior knowledge of results minimizes bias. The studies did not report whether an a priori protocol was produced and if so, whether it was followed.

4.3.9 A priori analysis plan

The studies did not report whether an a priori analysis plan was produced and if so, whether it was followed.

4.4.1 Primary outcome results

Drug use reduction was measured by percent of days of marijuana use in Waldron et al. (2001). The reported results indicate a positive effect favoring FFT on drug use frequency at 4-month follow up; SMD=0.78 (95% CI 0.25, 1.31) compared to CBT, and SMD=0.97 (95% CI 0.44, 1.51) compared to the group intervention.

The percent of days of marijuana use was not significantly different for the 7-month follow up; SMD=0.28 (95% CI -0.23, 0.79) compared to CBT, and SMD=0.04 (95% CI -0.46, 0.55) compared to the group intervention.

Numerical outcome results were not available in Friedman (1989).

4.4.2 Secondary outcome results

Family functioning and treatment retention was not reported in either of the included studies.

5.1 SUMMARY OF MAIN RESULTS

Our main objective was to evaluate the current evidence on the effect of FFT on drug use reduction for young people in treatment for non-opioid drug use.

Only one study provided data on drug use: this indicated a positive relative effect favoring FFT in comparison to CBT and a group intervention on drug use frequency at 4-month follow up, but no significant relative effect for the 7-month follow up.

Only one study reported results on education, comparing FFT and a parent group intervention on the change that mothers reported in the clients' academic problems. There was no significant difference between groups.

One study reported on delinquency. Results were mixed, indicating a positive relative effect favoring FFT at 4-month follow up compared to CBT, but no significant difference compared to the group intervention.

No significant relative effects of FFT were found for the 7-month follow up, compared to CBT or compared to the group intervention.

No studies reported on family functioning or retention. It was not possible to assess moderators of drug use reduction effects, or whether FFT works better for particular types of participants.

In short, we found there is currently insufficient evidence for conclusions to be drawn. The small number of available studies precludes any conclusions concerning effectiveness, ineffectiveness or potential damage of FFT for young people in treatment for non-opioid drug use.

5.2 OVERALL COMPLETENESS AND APPLICABILITY OF EVIDENCE

We found only two trials that examined whether FFT reduced youth drug use. Both studies were performed in the US. It was not possible to analyze the absolute effects of FFT as both studies compared FFT to other active treatments. Only one of the studies reported on the primary outcome of drug use reduction. Data on secondary outcomes were very limited.

It is important to consider program fidelity (i.e., compliance with program manual and requirements for therapist training) when evaluating the effects of an intervention such as FFT. Waldron et al., 2001, addressed treatment fidelity and reported that high adherence was achieved (see section 9.3 for a description of the method used). Friedman, 1989, considered the degree of adherence to the manual concerning the FFT intervention and reported that 3 percent of the therapist interventions were considered to be inconsistent with the functional method as described in the manual achieved (see section 9.3 for a description of the method used). A measurement of adherence to the parent group condition was not reported.

5.3 QUALITY OF THE EVIDENCE

Both studies were randomized controlled trials, although neither could be characterized as a robust RCT with low risk of bias on all assessed risk of bias items. The two included studies provided insufficient information on core issues to allow us to assess the risk of bias (e.g. allocation concealment and number of participants randomized) despite genuine efforts to contact the study authors. These methodological weaknesses may reflect inadequate reporting, flawed methodology, or both, and therefore compromise our confidence in the validity of the two studies.

5.4 LIMITATIONS AND POTENTIAL BIASES IN THE REVIEW PROCESS

The narrow search strategy performed in this review may limit the likelihood of identifying all relevant studies. However, we attempted to minimize the risk of missing relevant studies by conducting an extensive search of the grey literature, by extensive hand searching and by contacting international experts within the field. Indeed, the large number of grey literature and hand searches literature that has been assessed for relevance attests to this effort.

5.5 AGREEMENTS AND DISAGREEMENTS WITH OTHER STUDIES OR REVIEWS

The majority of the identified narrative reviews (Waldron & Turner, 2008; Vaughn & Howard, 2004; Austin, 2005; Ozechowski & Liddle, 2000) report that FFT-treatment shows evidence of positive effectiveness in drug use among youth. This is predominantly consistent with the current reviews results, although our confidence in these results is limited.

Two reviews (Waldron & Turner, 2008; Vaughn & Howard, 2004) include data on FFT from Friedman (1989) and conclude that FFT showed significant reductions in substance use of more than 50 % at follow up. Waldron & Turner (2008) classifies FFT as a well-established treatment for adolescent substance abuse based on Friedman (1989), Waldron et al. (2005) and Waldron & Slesnick et al. (2001).

Vaughn & Howard (2004) and Austin et al. (2008) indicate that youth participating in FFT demonstrated reductions in marijuana use from pre-treatment to post-treatment. These findings are consistent with Ozechowski & Liddle (2000), who conclude that improvements in self-reported drug use from intake to 4 months post-intake for FFT.

Consistent with our expectations, most of the reviews (Waldron & Turner, 2008;. Vaughn & Howard, 2004; Austin et al., 2005; Ozechowski & Liddle, 2000; Liddle, 2004; James, Alemi & Zepeda, 2013; Lipsey et al., 2010) state that it is not possible to decide whether or not FFT is more effective than other interventions for decreasing drug use. The reviews recommend further research which can evaluate the influence of FFT on abuse treatment outcomes.

6.1 IMPLICATIONS FOR PRACTICE AND POLICY

The current landscape of family therapy approaches for treatment of youth drug use shows that many initiatives have been tried. A certain inconsistency seems to be developing: while existing FFT programs have yet to be evaluated thoroughly, new FFT interventions continue to surface. This is not only costly, it is also risky, as initiatives backed only by unclear research could ultimately be damaging. It is therefore crucial to know more about the effectiveness of treatments to understand where money should be spent and to understand exactly what kind of support young drug users can benefit from. Further all the available evidence was US-based, and so the findings may not be generalizable to other settings and systems outside the US.

6.2 IMPLICATIONS FOR RESEARCH

Firstly, it is important to address the need for more research in the field. A small body of evidence exists in relation to the treatment of young drug users, with only a very modest number of controlled evaluations of treatments for this group, all conducted in the US. Well-designed, randomized controlled trials from diverse locations within this population are needed and should be reported clearly in accordance with the principles of the CONSORT 2010 statement.

Secondly, it is important to consider the possibility of adverse effects of these interventions. The popular belief is that FFT, as well as other family therapy approaches, is harmless, but very little research has been conducted that focuses on the potential harms of such family therapy approaches.